How many meters of a thin wire are required to manufacture a

7 A solenoid of length 20 cm area of cross section 40 cm and having 4000 turns is placed inside another solenoid of 2000 turns having a cross sectional area 8 0 cm and length 10 cm Find the mutual inductance between the solenoids Ho 200 of nodius R and having

A toroid is having 100 turns inner radius 9 cm and outer radius 11 cm then its self inductance is 1 2 H 2 Ho 2 3 Ho 5 4 5 Ho

Area of cross section of plane circular coil makes twice keeping it number of turns same then percantage increases in its self inductance 1 41 4 3 200 2 141 4 4 100

d low 1 A circuit contains a capacitor and inductance each with negligible resistance The capacitor is initially charged and the charging battery is disconnected At subsequent time the charge on the capacitor will b decrease exponentially a increase exponentially d remain constant c decrease linearly for limiting

A uniform and constant magnetic field B coming out of the plane of the paper exists in a rectangular region as shown in figure A conducting rod PQ is rotated about its mid point O with a uniform angular speed win the plane of the paper The emf EpQ induced between P and Q is best represented by the graph PQ P B

graph of B versus x abruptly 51 Sometimes we show an idealised magnetic field which is uniform in a given region and falls to zero One such field is represented in figure 35 E12 Using Ampere s law over the path PQRS show that such a field is not possible S 10 B Figure 35 E12 S Q R 59

of earth s magnetic A 255 m wide spaceship moves through the space at a speed 4 5 x 10 m s A magnetic field B 8 x 105T exists in the space in a direction parallel to the plane of motion Treating the spaceship as a conductor calculate the emf induced across its width

COMPREHENSION VIII A thin circular ring of mass m radius R has a uniformly distributed charge Q The ring is placed on a rough horizontal floor The coefficient of friction between the ring and the floor is u A uniform vertically upward magnetic field of radius greater than R and co axial with the ring exists in the space The magnetic field is changing as B Bot2 tesla where t is the time in second where Bo is a positive constant Now answer the following questions based on the above paragraph 26 C Choose the correct graph showing the variation of induced electric field with time t at the circumference of the ring A E B E E D Q M E B

2 A pair of coils of turns n and n are kept close together Current passing through the first is reducing at rate r and e m f 3 mV is developed across the other coil If the second coil carries current which is then reduced at the rate 2r the emf produced across the first coil will be 1 6n mV n 3 6 mV 2 6n2 mV n 3 4 mV

3 In a cylindrical region uniform magnetic field which is perpendicular to the plane of the figure is increasing with time and a conducting rod PQ is placed in the region Then a P will be at higher potential than Q b Q will be at higher potential than P d no omf will be developed