A metallic block carrying current I is subjected to a uniform magnetic induction $\stackrel{\rightharpoondown }{B}$ as shown in the figure. The moving charges experience a force  $\stackrel{\rightharpoondown }{F}$ given by ........... which results in the lowering of the potential of the face ........ Assume the speed of the carriers to be v

                   

(1) $eVB\hat{k}$ , ABCD                               

(2) $eVB\hat{k}$ , EFGH

(3) $-eVB\hat{k}$ , ABCD                             

(4) $-eVB\hat{k}$ , EFGH

Two insulated rings, one of slightly smaller diameter than the other are suspended along their common diameter as shown. Initially the planes of the rings are mutually perpendicular. When a steady current is set up in each of them

(1) The two rings rotate into a common plane

(2) The inner ring oscillates about its initial position

(3) The inner ring stays stationary while the outer one moves into the plane of the inner ring

(4) The outer ring stays stationary while the inner one moves into the plane of the outer ring

Two particles each of mass m and charge q are attached to the two ends of a light rigid rod of length 2R. The rod is rotated at constant angular speed about a perpendicular axis passing through its centre. The ratio of the magnitudes of the magnetic moment of the system and its angular momentum about the centre of the rod is:

1. $\frac{q}{2m}$                               

2. $\frac{q}{m}$

3. $\frac{2q}{m}$                              

4. $\frac{q}{\mathrm{\pi m}}$ 

A ring of radius R, made of an insulating material carries a charge Q uniformly distributed on it. If the ring rotates about the axis passing through its center and normal to the plane of the ring with constant angular speed $\omega$, then the magnitude of the magnetic moment of the ring is:

1. $Q\omega R^2$                       2. $\frac{1}{2}Q\omega R^2$

3. $Q{\omega }^{2}R$                       4. $\frac{1}{2}Q{\omega }^{2}R$

Three long, straight and parallel wires carrying currents are arranged as shown in the figure. The wire C which carries a current of 5.0 amp is so placed that it experiences no force. The distance of wire C from wire D is then 

1. 9 cm                                         

2. 7 cm 

3. 5 cm                                          

4. 3 cm

If m is the magnetic moment and B is the magnetic field, then the torque is given by

(1) $\overrightarrow{m}.\overrightarrow{B}$                      
(2) $\frac{\left|\overrightarrow{m}\right|}{\left|\overrightarrow{B}\right|}$
(3) $\overrightarrow{m}\times \overrightarrow{B}$                     
(4) $\left|\overrightarrow{m}\right|.\left|\overrightarrow{B}\right|$

What is the net force on the square coil?

(1) $1.67\times {10}^{-6}N$ moving towards wire

(2) $25\times {10}^{-7}N$ moving away from wire

(3) $35\times {10}^{-7}N$ moving towards wire

(4) $35\times {10}^{-7}N$ moving away from wire

A long wire A carries a current of 10 amp. Another long wire B, which is parallel to A and separated by 0.1m from A, carries a current of 5 amp, in the opposite direction to that in A. what is the magnitude and nature of the force experienced per unit length of B $({\mu }_0=4\mathrm{\pi }\times {10}^{-7}weber/amp-\mathrm{m})$

1. repulsive force of ${10}^{-4}N/m$

2. attractive force of ${10}^{-4}N/m$

3. repulsive force of $2\mathrm{\pi }\times {10}^{-5}\mathrm{N}/\mathrm{m}$

4. attractive force of $2\mathrm{\pi }\times {10}^{-5}\mathrm{N}/\mathrm{m}$

The relation between voltage sensitivity (${\sigma }_v$) and current sensitivity (${\sigma }_i$) of a moving coil galvanometer is (Resistance of Galvanometer = G) 

1. $\frac{{\sigma }_i}{G}={\sigma }_v$                           

2. $\frac{{\sigma }_v}{G}={\sigma }_i$

3. $\frac{G}{{\sigma }_v}={\sigma }_i$                           

4. $\frac{G}{{\sigma }_i}={\sigma }_v$

\(A,B, ~\text{and}~C\) are parallel conductors of equal length carrying currents \(I, I,~\text{and}~2I\) respectively. The distance between \(A\) and \(B\) is \(x\). The distance between \(B~\text{and}~C\) is also \(x\). \(F_1\) is the force exerted by \(B\) on \(A\) and \(F_2\) is the force exerted by \(C\) on \(A\) choose the correct answer:

                       
1. \(F_1 = 2F_2\)
2. \(F_2 = 2F_1\)
3. \(F_1 = F_2\)
4. \(F_1 = -F_2\)