# The radius of a loop as shown in the figure is $$10~\mathrm {cm}.$$ If the magnetic field is uniform and has a value $$10^{-2}~ T,$$ then the flux through the loop will be:   1. $$2 \pi \times 10^{-2}Wb$$ 2. $$3 \pi \times 10^{-4}Wb$$ 3. $$5 \pi \times 10^{-5}Wb$$ 4. $$5 \pi \times 10^{-4}Wb$$

Subtopic:  Magnetic Flux |
77%
From NCERT
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The dimensions of inductance are:

$1.$ $\left[ML{T}^{-2}{A}^{-2}\right]$
$2.$ $\left[M{L}^{2}{T}^{-2}{A}^{2}\right]$
$3.$ $\left[M{L}^{2}{T}^{-2}{A}^{-1}\right]$
$4.$ $\left[M{L}^{2}{T}^{-2}{A}^{-2}\right]$

Subtopic:  Self - Inductance |
69%
From NCERT
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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. $\frac{{\mu }_{0}I{l}^{2}}{2R}$

3. $\frac{{\mu }_{0}l{\mathrm{\pi R}}^{2}}{2l}$

4. $\frac{{\mu }_{0}{\mathrm{\pi R}}^{2}I}{l}$

Subtopic:  Magnetic Flux |
82%
From NCERT
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The net magnetic flux through any closed surface, kept in uniform magnetic field is:

1. Zero

2. $\frac{{\mu }_{0}}{4\mathrm{\pi }}$

3. $4{\mathrm{\pi \mu }}_{0}$

4. $\frac{4{\mu }_{0}}{\mathrm{\pi }}$

Subtopic:  Magnetic Flux |
94%
From NCERT
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The magnetic flux linked with a coil varies with time as $\varphi$ $=$ $2{t}^{2}-6t+5$, where $\varphi$ is in weber and t is in seconds. The induced current is zero at:

1. t = 0

2. t = 1.5 s

3. t = 3 s

4. t = 5 s

Subtopic:  Faraday's Law & Lenz Law |
90%
From NCERT
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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

Subtopic:  Motional emf |
61%
From NCERT
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Eddy currents are used in:

1. Induction furnace

2. Electromagnetic brakes

3. Speedometers

4. All of these

Subtopic:  Eddy Current |
94%
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The current through a choke coil increases from zero to 6 A in 0.3 seconds and an induced emf of 30 V is produced. The inductance of the coil is:

 1 5 H 2 2.5 H 3 1.5 H 4 2 H
Subtopic:  Self - Inductance |
89%
From NCERT
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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 $$I_{0}=10~A$$ and $\omega$ = 100$\pi$ rad/s. The maximum value of e.m.f. induced in the second coil is:

1. 5$\pi$ Volt

2. 2$\pi$ Volt

3. 4$\pi$ Volt

4. $\pi$ Volt

Subtopic:  Mutual Inductance |
81%
From NCERT
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A small square loop of wire of side 'l' is placed inside a large square loop of side 'L' (L$\gg$l). If the loops are coplanar and their centres coincide, the mutual inductance of the system is directly proportional to:

1. L/l

2. l/L

3. L2/l

4. l2/L

Subtopic:  Mutual Inductance |
72%
From NCERT
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