1. | \(\dfrac{heB}{\pi m}\) | 2. | \(\dfrac{heB}{2\pi m}\) |
3. | \(\dfrac{he}{\pi m}\) | 4. | \(\dfrac{he}{2\pi m}\) |
The ratio of the radii of two circular coils is \(1:2.\) The ratio of currents in the respective coils such that the same magnetic moment is produced at the centre of each coil is:
1. | \(4:1\) | 2. | \(2:1\) |
3. | \(1:2\) | 4. | \(1:4\) |
A uniform conducting wire of length \(12a\) and resistance '\(R\)' is wound up as a current-carrying coil in the shape of;
(i) | an equilateral triangle of side '\(a\)' |
(ii) | a square of side '\(a\)' |
The magnetic dipole moments of the coil in each case respectively are:
1. \(3Ia^2~\text{and}~4Ia^2\)
2. \(4Ia^2~\text{and}~3Ia^2\)
3. \(\sqrt{3}Ia^2~\text{and}~3Ia^2\)
4. \(3Ia^2~\text{and}~Ia^2\)
If the number of turns, area, and current through a coil are given by \(n\), \(A\) and \(i\) respectively then its magnetic moment will be:
1. \(niA\)
2. \(n^{2}iA\)
3. \(niA^{2}\)
4. \(\frac{ni}{\sqrt{A}}\)