Therefore, the magnetic field acts normally into the plane of the paper at the points inside the loop and normally out of the plane of paper at points outside the loop. The simple basic principle of flux compression can be applied in a variety of different ways. Systems using up to 25 modules have been developed at VNIIEF. Question 7. CM chokes are commonly used in industrial, electrical and telecommunications applications to remove or decrease noise and related electromagnetic interference.[4]. Solution: with Magnetic pole pair pieces. Magnetic field depicts how a moving charge flows around a magnetic object. (i) An electric motor converts mechanical energy into electrical energy. (a) generator. Physics Cup 2023 started on November 13th, 2022 13:00 UTC+0. Explosively pumped flux compression generator, Elementary description of flux compression. The screening currents also flow in this L-layer near the surface, creating magnetization M inside the superconductor, which perfectly compensates the applied field H, thus resulting in B = 0 inside the superconductor. In fact, one end of the solenoid behaves as a magnetic north pole, while the other behaves as the south pole. Well if this thing is moving to the right, when it's speed is 'v' it can be any units, meters per second, or whatever it is. The superconducting properties in each point of the superconductor are described by the complex quantum mechanical wave function (r,t) the superconducting order parameter. The amount of voltage induced depends on how fast the magnetic field lines are entering or leaving the coil. Why dont two magnetic lines of force intersect each other ? When the coil rotates, the shaft attached to it also rotates and therefore the electrical energy supplied to the motor is converted into the mechanical energy of rotation. R. Shankar, "Principles of Quantum Mechanics", eq. \(\overrightarrow{\mathrm{F}}=\mathrm{IL} \times \overrightarrow{\mathrm{B}}\) The direction of the induced current changes once in each: The magnetic field produced by a current carrying solenoid is very much similar to that of a bar magnet. Which sources produce alternating current ? (b) DC generator will generate a higher voltage. Another disadvantage was that the output voltage was very low, due to the single current path through the magnetic flux. Which of the following correctly describes the magnetic field near a long straight wire ? Other techniques exist which do not depend on explosives. (d) concentric circles near the point O but of elliptical shapes as we go away from it So, after half a revolution, side AB starts moving up and side DC starts coming down. Question 11 A wire called earth wire is used to connect the metal body of the electrical device to the earth, which is at zero potential. In household circuits, we have three wires, the live wire, the neutral wire and the earth wire. An electric motor is an electrical machine that converts electrical energy into mechanical energy.Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate force in the form of torque applied on the motor's shaft. a loop made of very thin ( L) superconducting wire or the cylinder with the similar wall thickness. Furthermore, the elementary charge also has a fixed value of e = 1.6021766341019C[12] to define the ampere. Here, the area under consideration can be of any size and under any orientation with respect to the direction of the magnetic field. An electric motor is based on the fact that when a current carrying conductor is placed in a magnetic field the conductor experiences a force which is given by Flemings Left Hand Rule. Therefore, now the force exerts downwards on the arm AB and upwards on the arm CD and thus again a couple of forces is formed that rotates the coil in clockwise direction. (i) When the current in the rod AB is increased, force exerted on the conductor increases, so the displacement of the rod increases. When too much current flows or short circuit these devices breaks the circuit. These are often seen on computer cables. Answer: The explosion travels as a wave through the middle of the armature cylinder. As the explosion makes its way through the cylinder, the cylinder comes in contact with the stator winding. The resistance of the circuit becomes zero and excessive current starts to flow through it. In total, each such Abrikosov vortex carries one quantum of magnetic flux 0. If the thumb and the first two fingers of right hand are held at right angles to each other, with the Forefinger held in the direction of the field, and the thumb in the direction of motion, the induced current I flows in the direction of the middle finger. A choke usually consists of a coil of insulated wire often wound on a magnetic core, although some consist of a doughnut-shaped "bead" of ferrite material strung on a wire. Solution: There are two carbon brushes B1 and B2 which press lightly against the two half rings. They were multi-field single-rotor devices with two or more sets of rotating contacts (either commutators or sliprings, as required), one to provide power to one set of armature windings to turn the device, and one or more attached to other windings to produce the output current. When does an electric short circuit occur ? The magnetic field inside a long straight solenoid-carrying current If the first finger points in the direction of magnetic field and the second finger in the direction of current, then the thumb will point in the direction of motion or the force acting on the conductor. Suppose that the generator coil ABCD is initially in the horizontal position. Radio frequency chokes (RFC) often have iron powder or ferrite cores which increases inductance and overall operation. It is expressed as the vector H and is measured in units of amperes per metre. Due to the change in the direction of motion of the two sides of the coil in the magnetic field after every half revolution, the direction of current produced in them also changes after every half revolution. (iii) As the coil rotates in the anticlockwise direction, the side AB of the coil moves down cutting the magnetic lines of force near the N-pole of the magnet, and side DC moves up, cutting the lines of force near the S-pole of the magnet. Question 37 The end of coil which was positive in the first half of rotation becomes negative in the second in the second half. Direction of magnetic field can be determined by using Right hand thumb rule. The discovery of the dynamo principle made industrial scale electric power generation technically and economically feasible. Solution: The magnetic flux value depends on the magnetic field direction and it is a vector quantity. (b) there is a momentary deflection in the galvanometer but it dies out shortly and there is no effect when the key is removed. The MK-2 generator is particularly interesting for the production of intense currents, up to 108A (100 MA), as well as a very high energy magnetic field, as up to 20% of the explosive energy can be converted to magnetic energy, and the field strength can attain 2106gauss (200 T). (ii) one revolution The reversed current reverses the direction of the forces acting on the two arms of the armature after every half rotation. A compass is to be placed near a bar magnet with unknown poles. Answer: A uniform magnetic field in a region is represented by drawing parallel straight lines, ail pointing in the same direction. Such generators can, if necessary, be utilised independently, or even assembled in a chain of successive stages: the energy produced by each generator is transferred to the next, which amplifies the pulse, and so on. On larger machines the constant magnetic field is provided by one or more electromagnets, which are usually called field coils{, Znobe Gramme reinvented Pacinotti's design in 1871 when designing the first commercial power plants operated in Paris. Solution: The spinning magnet was positioned so that its north and south poles passed by a piece of iron wrapped with insulated wire. 1. The side AB will come on the right hand side and start moving up whereas side DC will come on then the two commutator half rings R1 and R2 automatically change their contacts from one carbon brush to the other. Thus, a D. C. generator supplies a current in one direction by the use of a commutator consisting of two, half-rings of copper. At the time of short circuit, the current in the circuit Here the electron beam is moving from our back wall to the front wall, so the direction of current will be in the opposite direction, from front wall towards back wall or towards us. Question 36 Function of split ring : Split ring in a motor acts as a commutator, i.e., it reverses the flow of current in the circuit due to which the direction of the forces acting on the arms also reverses. The operating principle of electromagnetic generators was discovered in the years 18311832 by Michael Faraday.The principle, later called Faraday's law, is that an electromotive force is generated in an electrical conductor which encircles a varying magnetic flux.. (a) At X When coupled with the measurement of the von Klitzing constant RK = h/e2, this provided the most accurate values of Planck's constant h obtained until 2019. The first uses the sum of the number of pole pairs of the two rotors as the number of ferromagnetic stator rods, which will drive the secondary rotor the opposite direction of rotation of the primary. The battery energizes the windings just enough to imprint the residual field, to enable building up the current. (iv) After half revolution, the sides AB and DC of the coil will interchange their positions. The name comes from blocking"choking"high frequencies while passing low frequencies. An EPFCG package that could be easily carried by a person can produce pulses in the millions Question 8 This is due to the fact that the resultant force on a north pole at any point can be only in one direction. To convert the alternating current to DC, Pixii invented a commutator, a split metal cylinder on the shaft, with two springy metal contacts that pressed against it. They have since been replaced by alternators. Then our fingers will wrap around the conductor in the direction of the field lines of the magnetic field. The original "dynamo principle" of Werner von Siemens referred only to the direct current generators which use exclusively the self-excitation (self-induction) principle to generate DC power. The second mode has the number of stator pieces equal the difference between the pole pair counts of the rotors, which drives the secondary rotor the same direction as the primary. Answer: Question 4 However, the DM current flowing through the windings will generate high emitted near magnetic field since the windings are negative coupled in this case. Give reason. It passes differential currents, while blocking common-mode currents. However, in the early days of electric experimentation, alternating current generally had no known use. Thus, compass needle follows the path difference of magnetic field lines. Why does a compass needle get deflected when brought near a bar magnet ? For this reason, reducing the area of the surface enclosed by a closed loop conductor with a magnetic field passing through it, which would reduce the magnetic flux, results in the induction of current in the electrical conductor, which tends to keep the enclosed flux at its original value. (c) increases heavily. (c) The region with the highest density of magnetic field lines has the greatest strength. 8, p.4692, Bassani, R., 2007, Dynamic Stability of Passive Magnetic Bearings, Nonlinear Dynamics, V. 50, p.161-68, Tsurumoto, K., 1992, Basic Analysis on Transmitted Force of Magnetic Gear Using Permanent Magnet, IEEE Translation Journal on Magnetics in Japan, Vol 7, No. So the students who are in search of NCERT Solutions For Class 10 Science Chapter 13 Magnetic Effects Of Electric Current can refer to this article. What is the principle of an electric motor? The direction of magnetic field is : How do the strengths of the magnetic field at points X, Y and Z compare? Thus, the induced currents in the two sides of the coil are in the same direction, and we get an effective induced current in the direction BADC. On applying Flemings right hand rule to the side AB and DC of the coil, we find that the currents are in the direction B to A and D to C respectively. Solution: c) Half revolutions Which of the following property of a proton can change while it moves freely in a magnetic field? This is a list of sensors sorted by sensor type.. Acoustic, sound, vibration. (c) Nature of material inside solenoid i.e., B , Magnetic Field Due to a Circular Current Carrying Loop Alternating current is produced by AC generators of nuclear power plants, thermal power plants, hydroelectric power stations, etc. Sometimes due to excess heat or wear and tear, the live wire comes in direct contact with the metallic cover of the appliances, which can give an electric shock on touching them. Solution: [2] It was used by the firm of Elkingtons for commercial electroplating.[3][4][5]. Solution: (iv) Is the same at all points. (iii) Permanent magnets. This induces eddy currents in the conductors that creates a repulsive magnetic field which holds the two objects apart.. 6, pp. Answer: Fuse is the most important safety device, to avoid the overloading of domestic electric circuits. Question 5. Thus we have two parallel wires experiencing forces in opposite directions. Please note that we can also write D. C. dynamo in place of D. C. generator. Answer: In this way the electrical energy supplied to the motor is converted into the mechanical energy of rotation. Question 1 (iii) High power appliances like air-conditioner, refrigerator, a water heater, etc. It is a device used to convert mechanical energy in to electrical energy. Direction of force can be determined by Flemings left hand rule, right hand palm or screw rule, Electromagnet The earliest dynamos used permanent magnets to create the magnetic field. This design was inefficient, due to self-cancelling counterflows of current in regions of the disk that were not under the influence of the magnetic field. Therefore, power P = 1100 W = 1.1 KW The journal encourages greater interaction between the basic and applied sub-disciplines of magnetism d) Momentum This is referred to as flashing the field. Reese, G. A., 1967, Magnetic Gearing Arrangement. Solution: A stationary intermediate ferromagnetic cylinder allows a motion ratio due to the harmonic relationship between the number of poles input compared to output. A positively-charged particle (alpha particle) projected towards west is deflected towards north by a magnetic field. Space around a magnet in which magnetic effect is experienced. Magnetic flux is denoted by B where B is a magnetic field and its unit is Weber (Wb). [1] They are often wound in complex patterns (basket winding) to reduce self-capacitance and proximity effect losses. Which diagram show the poles in X, Y and Z? The nine field lines represent the magnetic flux threading the ring. This sets up induced current in coil B. And the end which was negative in the first half revolution becomes positive in the second half of revolution. The commutator is needed to produce direct current. Furlani, E. P., 2000, Analytical analysis of magnetically coupled multipole cylinders, J. Phys. a) Magnetic field due to a current through a straight conductor. Question 6 (ii) direction of force is towards north. They often have toroidal ferrite cores. When such a superconductor (now without any holes) is placed in a magnetic field with the strength between the first critical field Hc1 and the second critical field Hc2, the field partially penetrates into the superconductor in a form of Abrikosov vortices. What is the function of a split ring in an electric motor ? Then, the key is inserted and later removed. What is the function of brushes ? An intermediate ferromagnetic pole "stator" is usually held stationary between the rings, to direct the concentration of the magnetic lines between the high speed rotor and the low speed rotor. The electric oven draws a current given by (a) generator. The CM currents, however, see a high impedance because of the combined inductance of the positive coupled windings. The direction of the magnetic field is (i) AC generator has an electromagnet while a DC generator has permanent magnet 4, July 2001, p.284446, Charpentier, J. F., Lemarquand, G., 2001, Mechanical Behavior of Axially Magnetized Permanent-Magnet Gears, IEEE Transactions on Magnetics, Vol. To prevent from the shock the metallic part is connected to the earth through a three-pin plug due to which the current flows to the earth at the instant there is a short circuit. {\displaystyle A} What precaution should be taken to avoid the overloading of domestic electric circuits? The galvanometer is a current detecting and current measuring instrument. superconductor with the hole or superconducting loop/cylinder, the phase may continuously change from some value 0 to the value 0 + 2n as one goes around the hole/loop and comes to the same starting point. When it is conducting DM current, the equivalent current loops will generate inversed direction magnetic fields in space so that they tend to cancel each other. A simple A. C. generator consists of a rectangular coil ABCD that can be rotated rapidly between the poles N and S of a strong horseshoe type magnet M. The coil is made of a large number of turns of insulated copper wire. (iii) Half revolution. Draw magnetic field lines around a bar magnet? The iron core increases the inductance for a given volume of the core. Wire windings can conveniently produce any voltage desired by changing the number of turns, so they have been a feature of all subsequent generator designs, requiring the invention of the commutator to produce direct current. (iv) varies continuously In fact, this is one of the methods to demagnetise magnets. (c) The field at the centre of a long circular coil carrying current will be parallel straight lines true. Air flow meter; AFR sensor; Airfuel ratio meter Answer: Why is it necessary to earth metallic appliances? (iv) motor Phys., Vol. It is an application of electromagnetic induction. (c) The core of the solenoid in a circuit breaker must be made of a soft type magnetic material which can be strongly magnetised but does not retain induced magnetism. Solution: Question 27 They are started and operated in a manner similar to modern portable alternating current electric generators, which are not used with other generators on an electric grid. If the plastic insulation of the live wire and neutral wire gets torn, then the two wires touch each other. Answer: It converts electrical energy to mechanical energy. His dynamo used, instead of permanent magnets, two electromagnets placed opposite to each other to induce the magnetic field around the rotor. In the prototype of the single-pole electric starter, both the stationary and the revolving parts were electromagnetic. A magnetic dipole is a magnetic north pole and a magnetic south pole separated by a small distance. Question 18 Question 5 A longitudinal magnetic field is produced inside a hollow metallic conductor, by discharging a bank of capacitors into the solenoid that surrounds the cylinder. Explain different ways to induce current in a coil. Question 13 A spectrum analyzer connected to the probe collects data. The magnetic field lines pass along this normal core through the whole sample. To avoid the overloading of domestic electric circuits, the following precautions should be taken : (d) motor. (b) Using two bar magnets to stroke a steel bar The inverse of the flux quantum, 1/0, is called the Josephson constant, and is denoted KJ. An electric oven of 2 kW power rating is operated in a domestic electric circuit (220 V) that has a current rating of 5 A. Answer: Neuland, A. H., 1916, Apparatus for Transmitting Power. It is the constant of proportionality of the Josephson effect, relating the potential difference across a Josephson junction to the frequency of the irradiation. Question 16 103, Furlani, E. P., 1996, Analysis and optimization of synchronous magnetic couplings, J. Appl. [CBSE 2013, 2014] 2, June 2010, p.319-28, Linni Jian, K. T. Chau, Yu Gong, J. c) Velocity As the induced current attains its maximum, the fuse opening switch fuses and the load switch simultaneously closes, allowing the current to be delivered to the load (the mechanism for the operation of the load switch is not explained in available documentation). That is, a D. C. generator produces direct current and not alternating current. Question 39 Prior to the 2019 redefinition of the SI base units, the magnetic flux quantum was measured with great precision by exploiting the Josephson effect. In first half cycle the current flows in one direction by brush B1 and in second it flows in opposite direction by brush B2. The table below gives the results of the experiment when current is switched on and off. b) One revolution. P = 1100 W {\displaystyle \nabla \times \mathbf {A} =B} As opposed to conventional hard contact backlash in a spur gear, where a gear may rotate freely until in contact with the next gear, the Question 26 Answer: Both types of self-excited generator, which have been attached to a large external load while it was stationary, will not be able to build up voltage even if the residual field is present. Electric motor is used in the appliances like electric fans, washing machine, mixers, grinders, blenders, computers, MP3 players, etc. The current flows in the direction DCBA and leaves via the half ring B. If there is an attraction, then that end of the solenoid has south polarity and the other has north polarity. To monitor and control the current flowing through the inductor, a current clamp is clamped around the conducting wire. (a) The field consists of straight lines perpendicular to the wire. In magneto-explosive generators, the reduction in area is accomplished by detonating explosives packed around a conductive tube or disk, so the resulting implosion compresses the tube or disk. Answer: The cogs may be inter meshed to improve coupling. Constitutional Rights Foundation (CRF) is a non-profit, non-partisan, community-based organization. (a) the deflection in the galvanometer remains zero throughout. What is the direction of magnetic field? Electric Motor : The device used to convert electrical energy to mechanical energy is called Electric Motor. It is used in fans, machines, etc. The word was coined in 1831 by Michael Faraday, who utilized his invention toward making many discoveries in electricity (Faraday discovered electrical induction) and magnetism.[14][15]. State the principle of an electric generator. Answer: Now, if we look at our forefinger, it will be pointing upward. It used a permanent magnet which was rotated by a crank. The sides of the coil are interchanged, but rotate in the same anticlockwise direction. [CBSE (Delhi) 2017, AICBSE 2016] When a coil is rotated with respect to a magnetic field, the number of magnetic field lines through the coil changes. Together, these laws are enough to define the behavior of the electric field. When the conductor carries current in a direction perpendicular to the direction of the magnetic field, the force experienced by the conductor is largest. The difference between the balanced twisted windings CM choke and conventional balanced two winding CM choke is that the windings interact in the center of the core open window. Question 15 Question 9 [CBSE 2018] This indicates that the magnetic field is the same at all points inside the solenoid. It passes differential currents, while blocking common-mode currents. Similarly, the side SR of the coil will experience a downward force. Question 3 A signal generator, serving as a voltage source, is connected to an amplifier. b) Speed [, , , , , ] This review covers the various aspects of ferrofluids and ferrofluid-based emulsions, their preparation and properties are discussed in detail. These two forces form a couple which deflects the compass needle. Thus a unidirectional current is produced. If there is a repulsion, then that end of the solenoid has north polarity and the other end has south polarity because similar poles repel each other. Direct current machines like dynamos and commutated DC motors have higher maintenance costs and power limitations than alternating current (AC) machines due to their use of the commutator. Since, the magnetic field is circular. Question 18 (iii) Flemings right hand rule : Stretch the thumb, forefinger and the central finger of the right hand mutually perpendicular to each other. The phenomenon of electromagnetic induction is What will happen if a bar magnet is (i) Right hand thumb rule : If the current carrying conductor is held in the right hand such that the thumb points in the direction of the current, then the direction of the curl of the fingers will give the direction of the magnetic field. b) Magnetic field due to a current in a solenoid. By applying right hand thumb rule, we find that all the sections produce magnetic field downwards at all points inside the loop while at the outside points, the field is directed upwards. Why does a compass needle gets deflected when brought near a bar magnet? Let the current pass through the loop clockwise. (b) galvanometer. Self-excited direct current dynamos commonly have a combination of series and parallel (shunt) field windings, which are directly supplied power by the rotor through the commutator in a regenerative manner. He also built the first electromagnetic generator, called the Faraday disk, a type of homopolar generator, using a copper disc rotating between the poles of a horseshoe magnet. Ackermann, B., Honds, L., 1997, Magnetic drive arrangement comprising a plurality of magnetically cooperating parts which are movable relative to one another. The field electromagnets were also positioned on the sides of the armature disc rather than around the circumference.[12][13]. Two magnetic field lines do not intersect one another. The direction of the induced current changes once in each: Question 3. Thus, the galvanometer shows momentary deflections in opposite directions. Thus, the galvanometer shows momentary deflections in opposite directions. The commutator reverses the connection of the windings to the external circuit when the potential reverses so instead of alternating current, a pulsing direct current is produced. No. Why are we gonna have a change in magnetic flux, or a change in magnetic flux through the surface? Question 1 Solution: Chokes were frequently used in the design of rectifier power supplies for vacuum tube equipment such as radio receivers or amplifiers. Solution: Which of the following property of a proton can change while it moves freely in a magnetic field. An A.C generator generates an alternating current. 46, No. Properties of magnetic lines of force : Question 3 When current starts to flow, the coil ABCD is in horizontal position. A. Chvileva undertook the first experiment with this type of generator, with the goal of obtaining a very high magnetic field. If the cylinder has a positive charge, the end of the wire at the axis will have a negative charge. Question 21 According to this law, it is found that the force exerted on the part AB, pushes the coil downwards. (iv) is the same at all points (b) An electric generator works on the principle of electromagnetic induction true [4] Since flux is equal to the magnitude of the magnetic field multiplied by the area of the surface, as the surface area shrinks the magnetic field strength inside the conductor increases. This allowed the growth of a much more powerful field, thus far greater output power. What is the function of an earth wire? Microsoft pleaded for its deal on the day of the Phase 2 decision last month, but now the gloves are well and truly off. [6][7] It was also the discovery of the principle of dynamo self-excitation,[8] which replaced permanent magnet designs. If the forefinger points in the direction of magnetic field, thumb in the direction of motion of the conductor, then the middle finger points in the direction of current induced in the conductor. Steel saturates around 22,000 Gauss, while MuMetal saturates at about 8,000 Gauss. Question 6. Conductive metallic discs, assembled in facing pairs to create hollow modules having the form of a lined. A current is passed through inductor, and a probe measures the near field emission. Working of an A. C. generator Question 9. (iii) AC generator will generate a higher voltage The compression process partially transforms the chemical energy of the explosives into the energy of an intense magnetic field surrounded by a correspondingly large electric current. Read on to find out everything about NCERT Solutions For Class 10 Science Chapter 13 Magnetic Effects Of Electric Current. (d) the process of rotating a coil of an electric motor. Let the current pass through the loop clockwise. A coil of insulated copper wire is connected to a galvanometer. It provides the measurement of the total magnetic field that passes through a given surface area. Commutated machines cannot be used in low particulate or sealed applications or in equipment that must operate for long periods without maintenance. Solution: Answer: Question 17 An important development by Wilde and Siemens was the discovery (by 1866) that a dynamo could also bootstrap itself to be self-excited, using current generated by the dynamo itself. Adjust the hand in such a way that our mid finger points towards west (in the direction of current) and thumb points towards north (in the direction of force). They are frequently used as the first stage of a multi-stage generator, with the exit current used to generate a very intense magnetic field in a second generator. When a rectangular coil is placed in a magnetic field and current is passed through it, a force acts on the coil which rotates it continuously. This process is repeated again and again and the coil continues to rotate as long as the current is passing. These were referred to as "magneto-electric machines" or magnetos. Question 3 To avoid electric shocks, the metal body of an electrical device is earthed. Hemodialysis, also spelled haemodialysis, or simply dialysis, is a process of purifying the blood of a person whose kidneys are not working normally. (ii) does not change For lifting and transporting large masses of iron scrap. Question 9 Electricity could only be distributed over distances economically as alternating current (AC), through the use of the transformer. Also, converting alternating to direct current using rectifiers (such as vacuum tubes or more recently via solid state technology) is effective and usually economical. Yes, some current will be induced in the coil B. Answer: Generator [9] The use of electromagnets rather than permanent magnets greatly increased the power output of a dynamo and enabled high power generation for the first time. As shown in figure alongside, each section of wire produces its concentric set of lines of force. This type of gear consumes approximately 25% of its input power in the process, causing current in the external coils. Liang, N., 1972, Magnetic Transmission. After half rotation, the polarity of the commutator also changes, because now Q makes contact with brush X and P with brush Y. Question 2 The dynamo machine that was developed consisted of a stationary structure, which provides the magnetic field, and a set of rotating windings which turn within that field. (c) AC generator will generate a higher voltage. The reversal of current also reverses the direction of force acting on the two arms AB and CD. Solution: Give reason. This allows the armature coil to rotate continuously in the same direction. An external magnetic field (blue lines) threads a closed ring made of a perfect conductor (with zero resistance). After dynamos and motors were found to allow easy conversion back and forth between mechanical or electrical power, they were combined in devices called rotary converters, rotating machines whose purpose was not to provide mechanical power to loads but to convert one type of electric current into another, for example DC into AC. Electromagnetic induction, Induced potential difference, Induced current, Flemings right hand rule, Direct current,Alternating current, frequency of AC, Advantage of AC over DC, Domestic electric circuits. The Maxwell stress tensor (named after James Clerk Maxwell) is a symmetric second-order tensor used in classical electromagnetism to represent the interaction between electromagnetic forces and mechanical momentum.In simple situations, such as a point charge moving freely in a homogeneous magnetic field, it is easy to calculate the forces on the charge from the Lorentz (ii) Electromagnets The latest Lifestyle | Daily Life news, tips, opinion and advice from The Sydney Morning Herald covering life and relationships, beauty, fashion, health & wellbeing Electric fields are caused by electric charges, described by Gauss's law, and time varying magnetic fields, described by Faraday's law of induction. Electromagnetic Induction Solution: 2, March 2004, Jian, L., Chau, K. T., 2010, A Coaxial Magnetic Gear With Halbach Permanent-Magnet Arrays, IEEE Transactions on Energy Conversion, Vol. Dynamos were used in motor vehicles to generate electricity for battery charging. (a) A The current as seen from points A and B (in the plane of paper and on the axis of the coil) is anti-clockwise and clockwise, respectively. (d) vary continuously. The gear ratio between the rotors is the number of magnetic pole pairs on the high speed rotor to the number of magnetic pole pairs on the low speed rotor. The electric dynamo uses rotating coils of wire and magnetic fields to convert mechanical rotation into a pulsing direct electric current through Faraday's law of induction. If they did, it would mean that at the point of intersection, the compass needle would point towards two directions, which is not possible. Principle : NCERT Solutions for Class 10 Science Chapter 13 Magnetic Effects of Electric CurrentElectric motor works on the principle of force experienced by a current carrying conductor in a magnetic field. If the current in the coil A is changed, will some current be induced in the coil B ? (a) reduces substantially. There is a limit to the maximum current density and voltage which can be switched with a commutator. The switching action of the commutator causes, This page was last edited on 22 November 2022, at 06:15. The magnetic field due to solenoid depends upon Dynamos were the first electrical generators capable of delivering power for industry, and the foundation upon which many other later electric-power conversion devices were based, including the electric motor, the alternating-current alternator, and the rotary converter. For example, when a rectangular coil is placed in the magnetic field and current is passed through it, a torque acts on the coil, which rotates it continuously. By adding together the external magnetic field and the induced field, it can be shown that the net result is that the magnetic field lines originally threading the hole stay inside the hole, thus flux is conserved, and a current has been created in the conductive ring. the current flows across it. [citation needed] Wheatstone's design was similar to Siemens', with the difference that in the Siemens design the stator electromagnets were in series with the rotor, but in Wheatstone's design they were in parallel. Name some devices in which electric motors are used. (iv) Momentum Explain its principle and working. (ii) towards east [17] However, researchers found that stronger magnetic fields and thus more power could be produced by using electromagnets (field coils) on the stator. Two circular coils A and B are placed closed to each other. When key is inserted and removed, then the magnetic field lines passing through second coil increases and decreases in two cases respectively. Question 35 What result do you expect? direction of force is towards our right side. CRF seeks to instill in our nation's youth a deeper understanding of citizenship through values expressed in our Constitution and its Bill of Rights and to educate young people to become active and responsible participants in our society. No 9,337,712. Now that you are provided all the necessary information regarding NCERT Solutions For Class 10 Science Chapter 13 Magnetic Effects Of Electric Current and we hope this detailed article on magnetic effect of electric current class 12 ncert solutions is helpful. (c) If the length of the rod AB is increased there is no change in the displacement of the rod AB. Flemings left-hand rule states that, stretch the thumb, fore finger and middle finger of the left hand such that they are mutually perpendicular. What precautions should be taken to avoid the overloading of domestic electric circuits ? Since the direction of induced current in the coil is reversed after half revolution so the polarity (positive and negative) of the two ends of the coil also changes after half revolution. Correlated Magnetics Research, 2010, Company Website, Jae Seok Choi, Jeonghoon Yoo, Shinji Nishiwaki, and Kazuhiro Izui, 2010, Optimization of Magnetization Directions in a 3-D Magnetic Structure, IEEE Transactions on Magnetics, Vol. d) They are closed curves. The Ferromagnetic stator allows for two alternative modes. If the forefinger points in the direction of the magnetic field, the middle finger in the direction of current, then the thumb points in the direction of force in the conductor. This may be counterintuitive, since h is generally associated with the behavior of microscopically small systems, whereas the quantization of magnetic flux in a superconductor and the quantum Hall effect are both emergent phenomena associated with thermodynamically large numbers of particles. It is necessary to earth metallic appliances because it ensures that if there is any current leakage in the metallic cover, the potential of the appliance becomes equal to that of the earth. Thus, in 1 revolution of the coil, the current changes its direction 2 times. As with the mode 3 device, it consumes approximately 25% of the energy to supply the variable input, however if the variable input is held stationary the device functions as a mode 2 device. 0,687,292[1] and developed further from the 1940s[2][3]. Answer: Geophone; Hydrophone; Microphone; Pickup; Seismometer; Sound locator; Automotive. Question 8. (iv) False. (d) The field consists of concentric circles centred on the wire. Different ways to induce current in a coil are : Question 1 B Question 23 Learn how and when to remove these template messages, Learn how and when to remove this template message, "Cam drive apparatus having a magnetic gear", http://www.gedrivetrain.com/insideDP27.cfm, http://www.bostongear.com/pdf/product_sections/200_series_helical.pdf, https://www.youtube.com/watch?v=m4m81JjZCJo, https://www.youtube.com/watch?v=3xUm25CNNgQ, https://en.wikipedia.org/w/index.php?title=Magnetic_gear&oldid=1118007531, Cleanup tagged articles with a reason field from April 2015, Wikipedia pages needing cleanup from April 2015, Wikipedia introduction cleanup from April 2015, Articles covered by WikiProject Wikify from April 2015, All articles covered by WikiProject Wikify, Articles lacking reliable references from April 2015, Articles needing additional references from April 2015, All articles needing additional references, Articles with multiple maintenance issues, Creative Commons Attribution-ShareAlike License 3.0, Shear / overload proof mechanical coupling, Wear is limited to bearings, not mating contact surfaces of gears. Therefore, an electric oven of 2 KW power rating cannot be operated in a domestic electric circuit (220 V) that has a current rating of 5 A because electric oven has higher power than the power of the electric circuit. The magnetic flux frozen in a loop/hole (plus its L-layer) will always be quantized. Question 3 Shop by department, purchase cars, fashion apparel, collectibles, sporting goods, cameras, baby items, and everything else on eBay, the world's online marketplace The same conversion tasks are now performed by solid state power semiconductor devices. Power Appl., Vol. Answer: b) Towards east Explain. The mode 4 device is a modification to the mode 3 device where a low torque variable speed input, a high torque mechanical input, and a high torque mechanical output. 79, p. 23, 'Ampre's Inductive Results', Michael Faraday, D.C.L, F.R.S. In the second type of generator (MK-2, 1952), the magnetic flux, confined between the windings of the external conductor and a central conductive tube filled with explosive, is compressed by the conical 'piston' created by the deformation of the central tube as the detonation wave travels across the device. Question 19 It generates alternating current that changes its polarity after every half rotation. (c) Magnetic field lines always point from North pole to South pole around the magnet. The induced current is found to be the highest when the direction of motion of the coil is at right angles to the magnetic field. Due to this change, the current keeps flowing in the same direction in the other circuits. However, the north and south poles of the magnet induced currents in opposite directions. Solution: d) is the same at all points [10] Further improvements were made on the Gramme ring, but the basic concept of a spinning endless loop of wire remains at the heart of all modern dynamos. This is known as Right-hand thumb rule. This includes converting between direct current (DC) and alternating current (AC), three phase and single phase power, 25Hz AC and 60Hz AC, or many different output voltages at the same time. Choose the correct option : A rectangular coil of copper wires is rotated in a magnetic field. Due to Faraday's law of induction, the motion of the wire within the magnetic field creates an electromotive force, which pushes on the electrons in the metal, creating an electric current in the wire. Thus, the choke presents little inductance or impedance to DM currents. The side AB will come on the right hand side and DC will come on the left side. Explain different ways to induce current in a coil. Question 16 Solution: Name two safety measures commonly used in electric circuits and appliances. Question 1 One end of the earth wire is connected to the device and the other end of the wire is connected to the earth. = The electric generator works on the principle that when a straight conductor is moved in a magnetic field, then current is induced in the conductor. (d) The field consists of concentric circles centred on the wire. If the key in the arrangement as shown below is taken out (the circuit is made open) and magnetic field lines are drawn over the horizontal plane ABCD, the lines are [NCERT Exemplar] A rectangular coil of copper wires is rotated in a magnetic field. (c) weaker at Y than Z, stronger at Y than Z a) Mass [citation needed] They require a starting current pulse to operate, usually supplied by capacitors. Pixii found that the spinning magnet produced a pulse of current in the wire each time a pole passed the coil. While the force exerted on the part CD pushes it upwards. 105, Mezani, S., Atallah, K., Howe, D., 2006, A high-performance axial-field magnetic gear, Journal of Applied Physics Vol. Question 33 The magnetic field of the magnet exerts force on both the poles of the compass needle. 21.1.44, London's magnetic field penetration depth, Committee on Data for Science and Technology, "2018 CODATA Value: magnetic flux quantum", "2018 CODATA Value: conventional value of Josephson constant", "Quantized Magnetic Flux in Superconductors: Experiments confirm Fritz London's early concept that superconductivity is a macroscopic quantum phenomenon", "The Feynman Lectures on Physics Vol. Solution: (i) As a bar magnet is pushed into the coil, a momentary deflection is observed in the galvanometer indicating the production of a momentary current in the coil. Answer: Flux quantization also plays an important role in the physics of type II superconductors. So the candidates who want to secure a decent grade in class 10 board exams can refer to this article and solve magnetic effect of electric current science class 10 NCERT solutions. What is Magnetic Flux? Name two safety measures commonly used in electric circuits and appliances. a) Magnetic lines are directed from the north pole towards the south pole. (i) A deflection is observed in the galvanometer due to the induced current because of the changing magnetic flux (increasing) through the turns of the coil connected to the galvanometer. (d) A wire with a green insulation is usually the live wire of an electric supply true. gives: Now, because the order parameter must return to the same value when the integral goes back to the same point, we have:[10]. A longitudinal magnetic field is produced in between a metallic conductor and a surrounding solenoid, by discharging a battery of capacitors into the solenoid; After the charge is ignited, a detonation wave propagates in the explosive charge placed in the interior of the central metallic tube (from left to right on the figure); Under the effect of the pressure of the detonation wave, the tube deforms and becomes a cone which contacts the helically wrapped coil, diminishing the number of turns not short-circuited, compressing the magnetic field and creating an inductive current; At the point of maximal flux compression, the load switch is opened, which then delivers the maximal current to the load. Answer: How does a solenoid behave like a magnet? The two ends of the coil are connected to the two copper half rings (or split rings) R1 and R2 of a commutator. In the latter case, the flux has a quantum different from 0. To reduce the near magnetic field emission, a twisted winding structure can be applied to the CM choke. The essential difference between an AC generator and a DC generator is that: should not be used simultaneously. Solution: (a) Current in rod AB is increased? 44, No. In this case, the leakage flux, which is also the near magnetic field emission of the CM choke is low. Such a device can be termed a torque multiplier. A motor works on the principle of magnetic effect of current. A dynamo has the disadvantages of a mechanical commutator. ; Reprinted From The Philosophical Transactions Of 1846-1852, with other Electrical Papers from the Proceedings of the Royal Institution and Philosophical Magazine, Richard Taylor and William Francis, Printers and Publishers to the University of London, Red Lion Court, Fleet Str., London, England (1855). The direction of force exerted on the coil can be found through Flemings left hand law. It is a functional name; the name "choke" is used if an inductor is used for blocking or decoupling higher frequencies, but the component is simply called an "inductor" if used in electronic filters or tuned circuits. It 10, October 2009, p.4526-29. As the slip rings R1 and R2 rotate with the coil, the two pieces of carbon called brushes, B1 and B2, keep contact with them. Record of the 2005 IEEE Industry Applications Conference, p.261-5, Krasil'nikov, A. As a result magnetic gears are able to apply pressure no matter the relative angle. Question 30 Answer: (i) pushed into the coil, e) In the uniform magnetic field, the lines of force are parallel to one another. Thus, the induced currents in the two sides of the coil are in the same direction, and we get an effective induced current in the direction BADC. (iii) When the length of the rod AB is increased, force exerted on the conductor increases, so the displacement of the rod increases. An explosively pumped flux compression generator (EPFCG) is a device used to generate a high-power electromagnetic pulse by compressing magnetic flux using high explosive.. An EPFCG only ever generates a single pulse as the device is physically destroyed during operation. Answer: Dynamos still have some uses in low power applications, particularly where low voltage DC is required, since an alternator with a semiconductor rectifier can be inefficient in these applications. State the principle of an electric generator. Draw a labelled diagram of an electric motor. In case of a homogeneous magnetization, the problem can be simplified at least in (b) strength of current i.e, B I Electrodynamic suspension (EDS) is a form of magnetic levitation in which there are conductors which are exposed to time-varying magnetic fields. Answer: They are often constructed similarly to transformers, with laminated iron cores and an air gap. Question 1 Question 4 (iv) Upward. (iii) Velocity [17] The field coils of the stator were originally separately excited by a separate, smaller, dynamo or magneto. 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