The coefficient of mutual inductance between two coils depends upon:
1. | medium between coils |
2. | separation between coils |
3. | orientation of coils |
4. | All of these |
1. | \(\dfrac{L}{l}\) | 2. | \(\dfrac{l}{L}\) |
3. | \(\dfrac{L^2}{l}\) | 4. | \(\dfrac{l^2}{L}\) |
Two coils have a mutual inductance of \(5\) mH. The current changes in the first coil according to the equation \(I=I_{0}\cos\omega t,\) where \(I_{0}=10~\text{A}\) and \(\omega = 100\pi ~\text{rad/s}\). The maximum value of emf induced in the second coil is:
1. \(5\pi~\text{V}\)
2. \(2\pi~\text{V}\)
3. \(4\pi~\text{V}\)
4. \(\pi~\text{V}\)
1. | \(5\) H | 2. | \(2.5\) H |
3. | \(1.5\) H | 4. | \(2\) H |
Eddy currents are used in:
1. Induction furnace
2. Electromagnetic brakes
3. Speedometers
4. All of these
A short magnet is allowed to fall along the axis of a horizontal metallic ring. Starting from rest, the distance fallen by the magnet in one second may be:
1. | \(4\) m | 2. | \(5\) m |
3. | \(6\) m | 4. | \(7\) m |
The magnetic flux linked with a coil varies with time as \(\phi = 2t^2-6t+5,\) where \(\phi \) is in Weber and \(t\) is in seconds. The induced current is zero at:
1. | \(t=0\) | 2. | \(t= 1.5~\text{s}\) |
3. | \(t=3~\text{s}\) | 4. | \(t=5~\text{s}\) |
The net magnetic flux through any closed surface, kept in uniform magnetic field is:
1. | zero | 2. | \(\dfrac{\mu_{0}}{4 \pi}\) |
3. | \(4\pi μ_{0}\) | 4. | \(\dfrac{4\mu_{0}}{\pi}\) |
If a current is passed through a circular loop of radius \(R\) then magnetic flux through a coplanar square loop of side \(l\) as shown in the figure \((l<<R)\) is:
1. | \(\frac{\mu_{0} l}{2} \frac{R^{2}}{l}\) | 2. | \(\frac{\mu_{0} I l^{2}}{2 R}\) |
3. | \(\frac{\mu_{0} l \pi R^{2}}{2 l}\) | 4. | \(\frac{\mu_{0} \pi R^{2} I}{l}\) |