A charge \(Q\) is uniformly distributed on a ring of radius \(R\) made of an insulating material. If the ring rotates about the axis passing through its centre and normal to the plane of the ring with constant angular speed \(\omega\), then what will be the magnitude of the magnetic moment of the ring?
1. \(Q \omega R^{2}\)
2. \(\frac{1}{2} Q \omega R^{2}\)
3. \(Q \omega^{2} R\)
4. \(\frac{1}{2} Q\omega^{2} R\)$$

What happens when the number of turns in a galvanometer is doubled?

The two parts of the loop are circles of radii \(2a\) and \(a,\) respectively, and carry the same current \(i\) as shown in the given figure. What is the magnitude of the dipole moment of the current loop?

1. \(5 \pi a^{2}\hat i\) 
2. \(4 \pi a^{2}\hat i\) 
3. \(3 \pi a^{2}\hat i\) 
4. zero

What is the magnetic moment of the following current loop?
            
1. \(24~\text{Am}^2\)
2. \(12~\text{Am}^2\)
3. \(6~\text{Am}^2\)
4. zero

                
1. \(\mu_{0} i_{1} i_{2}\)
2. \(\dfrac{\mu_{0} i_{1} i_{2}}{\pi}\)
3. \(\dfrac{\mu_{0} i_{1} i_{2}}{2 \pi}\)
4. \(2 \mu_{0} i_{1} i_{2}\) 

If a long hollow copper pipe carries a direct current along its length, then the magnetic field associated with the current will be:

A charged particle is projected through a region in a gravity-free space. If it passes through the region with constant speed, then the region may have:
1. \(\vec{E}=0, \vec{B} \neq 0\)
2. \(\vec{E} \neq 0, \vec{B} \neq 0\)
3. \(\vec{E} \neq 0, \vec{B}=0\)
4. Both (1) & (2)