In a coil of resistance \(10\) \(\Omega\), the induced current developed by changing magnetic flux through it is shown in the figure as a function of time. The magnitude of change in flux through the coil in Weber is:
1. \(2\)
2. \(6\)
3. \(4\)
4. \(8\)
The figure shows planar loops of different shapes moving out of or into a region of a magnetic field which is directed normally to the plane of the loop away from the reader. Then:
1. | for the rectangular loop abcd, the induced current is clockwise. |
2. | for the triangular loop abc, the induced current is clockwise. |
3. | for the irregularly shaped loop abcd, the induced current is anti-clockwise. |
4. | none of these. |
A wheel with \(10\) metallic spokes each \(0.5\) m long is rotated with a speed of \(120\) rev/min in a plane normal to the horizontal component of earth’s magnetic field HE at a place. If \(H_E=0.4\) G at the place, what is the induced emf between the axle and the rim of the wheel? (\(1\) G=\(10^{-4}\) T)
1. \(5.12\times10^{-5}\) T
2. \(0\)
3. \(3.33\times10^{-5}\)
4. \(6.28\times10^{-5}\)
Two concentric circular coils, one of small radius \({r_1}\) and the other of large radius \({r_2},\) such that \({r_1<<r_2},\) are placed co-axially with centres coinciding. The mutual inductance of the arrangement is:
1. \(\dfrac{\mu_0\pi r_1^2}{3r_2}\)
2. \(\dfrac{2\mu_0\pi r_1^2}{r_2}\)
3. \(\dfrac{\mu_0\pi r_1^2}{r_2}\)
4. \(\dfrac{\mu_0\pi r_1^2}{2r_2}\)
The expression for the magnetic energy stored in a solenoid in terms of magnetic field \(B\), area \(A\) and length \(l\) of the solenoid is:
1. | \( \dfrac{1}{\mu_0}B^2Al\) | 2. | \( \dfrac{1}{2\mu_0}B^2Al\) |
3. | \( \dfrac{2}{\mu_0}B^2Al\) | 4. | \( \dfrac{3}{2\mu_0}B^2Al\) |
A rod of length \(l\) rotates with a uniform angular velocity \(\omega\) about its perpendicular bisector. A uniform magnetic field \(B\) exists parallel to the axis of rotation. The potential difference between the two ends of the rod is:
1. zero
2. \(\frac{1}{2}Bl\omega ^{2}\)
3. \(Bl\omega ^{2}\)
4. \(2Bl\omega ^{2}\)
A conducting rod is moved with a constant velocity \(v\) in a magnetic field. A potential difference appears across the two ends,
a. | \(\overrightarrow v \|\overrightarrow l\) | ifb. | if \(\overrightarrow v \|\overrightarrow B\) |
c. | \(\overrightarrow l \|\overrightarrow B\) | ifd. | none of these |
Choose the correct option:
1. | (a), (b) | 2. | (b), (c) |
3. | (d) only | 4. | (a), (d) |
1. | \(vBl\) | 2. | \(vBl \over 2\) |
3. | \({\sqrt 3 \over 2}vBl\) | 4. | \({1 \over \sqrt 3}vBl\) |