Q. No.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. | \(\dfrac{4\mu_{0}}{\pi}\) |
A circular disc of radius \(0.2\) m is placed in a uniform magnetic field of induction \(\frac{1}{\pi} \left(\frac{\text{Wb}}{\text{m}^{2}}\right)\) in such a way that its axis makes an angle of \(60^{\circ}\) with \(\vec {B}.\) The magnetic flux linked to the disc will be:
| 1. | \(0.02\) Wb | 2. | \(0.06\) Wb |
| 3. | \(0.08\) Wb | 4. | \(0.01\) Wb |
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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. | \(\frac{\mu_{0} \pi R^{2} I}{l}\) |
The radius of a loop as shown in the figure is \(10~\text{cm}.\) If the magnetic field is uniform and has a value \(10^{-2}~ \text{T},\) then the flux through the loop will be:
| 1. | \(2 \pi \times 10^{-2}~\text{Wb}\) | 2. | \(3 \pi \times 10^{-4}~\text{Wb}\) |
| 3. | \(5 \pi \times 10^{-5}~\text{Wb}\) | 4. | \(5 \pi \times 10^{-4}~\text{Wb}\) |
What is the dimensional formula of magnetic flux?
1. \(\left[ M L^2 T^{-2}A^{-1}\right]\)
2. \(\left[ M L^1 T^{-1}A^{-2}\right]\)
3. \(\left[ M L^2 T^{-3}A^{-1}\right]\)
4. \(\left[ M L^{-2} T^{-2}A^{-2}\right]\)
A square of side \(L\) meters lies in the \(XY\text-\)plane in a region where the magnetic field is given by \(\vec{B}=B_{0}\left ( 2\hat{i} +3\hat{j}+4\hat{k}\right )\text{T}\) where \(B_{0}\) is constant. The magnitude of flux passing through the square will be:
1. \(2 B_{0} L^{2}~\text{Wb}\)
2. \(3 B_{0} L^{2}~\text{Wb}\)
3. \(4 B_{0} L^{2}~\text{Wb}\)
4. \(\sqrt{29} B_{0} L^{2}~\text{Wb}\)
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| 1. | directly proportional to \(i\). |
| 2. | directly proportional to \(R\). |
| 3. | directly proportional to \(R^2\). |
| 4. | Zero. |
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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. | \(t=5~\text{s}\) |
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A coil having number of turns \(N\) and cross-sectional area \(A\) is rotated in a uniform magnetic field \(B\) with an angular velocity \(\omega\). The maximum value of the emf induced in it is:
1. \(\frac{NBA}{\omega}\)
2. \(NBAω\)
3. \(\frac{NBA}{\omega^{2}}\)
4. \(NBAω^{2}\)
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The current in a coil varies with time \(t\) as \(I= 3 t^{2} +2t\). If the inductance of coil be \(10\) mH, the value of induced emf at \(t=2~\text{s}\) will be:
1. \(0.14~\text{V}\)
2. \(0.12~\text{V}\)
3. \(0.11~\text{V}\)
4. \(0.13~\text{V}\)
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