# Electromagnetic Induction Questions and Answers

Physics

Electromagnetic InductionA copper ring is placed co axially in a time varying cylindrically symmetric magnetic field given by B btk Radius of ring is r Resistance of one half of the ring is double that of remaining half The magnitude of the electric field conservative inside the copper br Find K b K ring is E 42 Art

Physics

Electromagnetic InductionA single phase transformer is connected to a 230 volt 50Hz supply The net cross sectional area of the core is 60 mm The number of turns of the primary is 500 And in secondary 100 Determine a Transformation ration b EMF in the secondary

Physics

Electromagnetic InductionOne solenoid is centered inside another The outer one has a length of 50 0 cm and contains 6750 coils while the coaxial inner solenoid is 3 0 cm long and cm in area and contains 150 coils The current in the outer solenoid is changing at 3000 A s Find the emf induced in V in the inner solenoid Round off to nearest integer

Physics

Electromagnetic InductionWhen north pole of a magnet is moved to the plane of the coil as shown perpendicular in figure then Induced Current NAN A B Capacitor S a emf is induced b Induced current flows from B to A along the coil when A and B are connected through resistor c Electrons flow from A to B along the coil d Hence plate A will become positively charged

Physics

Electromagnetic InductionIn the given branch PQ of a circuit shown in figure a current i 5t 5 A is flowing where t is in second The potential difference between points P and Q Vp Vo at t 1 s is 10 V Q 15 V 15 V 12 V mmm L 1 Hi R 292 P

Physics

Electromagnetic InductionA solenoid has an inductance of 5 H and a resistance of 1 0 Q connected to a battery of emf 10 V The time taken for the magnetic energy to reach of its maximum value is approximately 1 8 s 2 7 S 3 5 s 4 2 S

Physics

Electromagnetic InductionWire 1 is now removed and Wire 2 is exposed to a magnetic field of strength 73 mT such that the magnetic field lines make an angle to the wire as shown in Figure Q3c The current in Wire 2 has the same magnitude as in b and flows downwards Wire 2 experiences a magnetic force of magnitude 859 uN c Determine the direction of this magnetic force stating the name of the rule which you use to determine this and calculate Figure Q3c Orientation of magnetic field lines around Wire 2 The current supplied to Wire 2 is now switched off It is placed in a region of magnetic field strength 415 mT where the wire can be moved at a constant speed v in the horizontal plane either to the left or to the right as shown in Figure Q4d During this process an emf of 0 10 V is induced across the ends of the wire and the top end of the wire acquires a positive charge d Calculate the velocity of the wire including a direction and state the rule used to determine this direction B H 3 3

Physics

Electromagnetic InductionA coil of inductance L and zero resistance is connected to a source of variable emf at t 0 The emf of the source is varied with time according to the graph shown on the right above What will be the average current that flows through the coil during time T A VT 2L A B VT 3L T C 3V T 2L D VT L eing at a rate of 4 A s through a coil of inductance

Physics

Electromagnetic Induction5 A long straight wire carries a steady current I and a metal bar with length I is moving at a constant velocity v as shown in figure Point a is at a distance d from the wire i Calculate the emf induced in the bar ii Which point a orb is at higher potential iii If the bar is replaced by a rectangular wire loop of resistance R what is the magnitude of the current induced in the loop d a b V I d W V

Physics

Electromagnetic Inductionis kept rotating with a constant angular speed w in a vertical plane about a horizontal axis at the end O The free end A is arranged to slide without friction along a fixed conducting circular ring in the same plane as that of rotation A uniform and constant magnetic induction B is applied perpendicular and into the plane of rotation as shown in figure An inductor L and an external resistance R are connected through a switch S between the point O and a point on the ring to form an electrical circuit Neglect the resistance of the ring and the rod Initially the switch is open What is the induced emf across the terminals of the switch i Obtain an expression for the current as a function of time after switch S is closed ii Obtain the time dependence of the

Physics

Electromagnetic Induction6 ELECTROMAGNETIC INDUCTION The directions of induced current in coil for different kinds of motion of magnets a S S b S N c N N Clockwise induced current S Clockwise induced current s No S No induced current because there is no change of flux linked with

Physics

Electromagnetic InductionIn the circuit shown in Fig The capacitor has capacitance C 20 F and is initially charged to 100 V with the polarity shown The resistor Ro has resistance 100 at time t 0 the switch is closed The smaller circuit is not connected in any way to the larger one The wire of the smaller circuit is not connected in any way to the larger one The wire of the smaller circuit has a resistance of 1 0wm and contains 25 loops The larger circuit is rectangle 2 0 m by 4 0 m while the smaller one has dimensions a 10 0 cm and b 20 0 cm The distance c is 5 0 cm The figure is not drawn to scale Both circuits are held stationary Assume that only wire nearest to the smaller circuit produces an appreciable magnetic field through it The current in the larger circuit 200ms

Physics

Electromagnetic InductionA student constructs an inductor shown in Figure Q1a by winding an insulated metal wire around a core of soft magnetic material ferrite The cylindrical coil has 9 turns a length of 458 mm and a diameter of 16 mm The core has a relative permeability of 325 and negligible resistance End Y End X End P 17 End Q Figure Q1a A cylindrical coil inductor resistor At t 0 s the student completes a series circuit by connecting end X of the wire to the positive terminal of a power supply and end Y to a 10 that was connected to the negative terminal of the supply The power supply has an emf of 12 V and a negligible internal resistance a i Show that the inductance of this inductor is approximately 15 H Calculate the time constant of this LR circuit ii iii Calculate the current in the circuit at time t 3 us Calculate the time taken for the current in the circuit to reach 1 1 A The student leaves the inductor connected to the power supply until the current reaches a steady value b i i ii iii Calculate the magnitude of the magnetic field strength inside the inductor Which end P or Q of the inductor is the North pole State the name of the rule you have used to determine this How much magnetic flux is coming out of the North pole of the inductor Calculate the amount of energy stored within the magnetic field of the inductor

Physics

Electromagnetic InductionWhen a magnet is allowed to fall through two identical metal coils at different temperatures then magnet falls slowly through the coil at low temperature as its resistance is less more induced current flows so more is the opposition A magnet all 50

Physics

Electromagnetic InductionImagine a cone of height h and radius R placed in a uniform electric field E parallel to its axis What is the ratio of electric flux through the flat surface of the cone and the curved surface of the cone 1 2 2 3 3 1 for 4

Physics

Electromagnetic InductionZero An infinitely long wire carries current i along z axis Find flux through the right angled isosceles trangular region coplanar with the wire as shown in figure id xid xy loo 93 47 14 E OF X 2 Jw 2 10 a a a C BA Su through the hemispherical surface