Electromagnetic Induction · Question 20

A solenoid having area A and length 'l' is filled with a material having relative permeability 2. The magnetic energy stored in the solenoid is :

1. B2Al4 0
2. B2Al2 0
3. B2Al 0
4. B2Al

A coil of area A and N turns is rotating with angular velocity in a uniform magnetic field B about an axis perpendicular to B. Magnetic flux and induced emf across it, at an instant when B is parallel to the plane of coil, are :

1. = AB, = NAB
2. = AB, = 0
3. = 0, = 0
4. = 0, = NAB

Consider I1 and I2 are the currents flowing simultaneously in two nearby coils 1 & 2, respectively. If L1 = self inductance of coil 1, M12 = mutual inductance of coil 1 with respect to coil 2, then the value of induced emf in coil 1 will be :

1. e1 = -L1 dI2dt - M12 dI1dt
2. e1 = -L1 dI1dt + M12 dI2dt
3. e1 = -L1 dI1dt - M12 dI1dt
4. e1 = -L1 dI1dt - M12 dI2dt

A uniform magnetic field of 0.4 T acts perpendicular to a circular copper disc 20 cm in radius. The disc is having a uniform angular velocity of 10 rad s-1 about an axis through its centre and perpendicular to the disc. What is the potential difference developed between the axis of the disc and the rim? ( = 3.14)

1. 0.5024 V
2. 0.0628 V
3. 0.2512 V
4. 0.1256 V

[figure] A conducting bar moves on two conducting rails as shown in the figure. A constant magnetic field B exists into the page. The bar starts to move from the vertex at time t = 0 with a constant velocity. If the induced EMF is E tn, then value of n is .