# A conducting square frame of side $$a$$ and a long straight wire carrying current $$I$$ are located in the same plane as shown in the figure. The frame moves to the right with a constant velocity $$v.$$ The emf induced in the frame will be proportional to:       1. $$\frac{1}{x^2}$$ 2. $$\frac{1}{(2 x-a)^2}$$ 3. $$\frac{1}{(2 x+a)^2}$$ 4. $$\frac{1}{(2 x-a)(2 x+a)}$$

Subtopic: Â Motional emf |
Â 72%
From NCERT
NEET - 2015
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A thin semicircular conducting the ring $$(PQR)$$ of radius $$r$$ is falling with its plane vertical in a horizontal magnetic field $$B,$$ as shown in the figure. The potential difference developed across the ring when it moves with speed $$v$$ is:

 1 zero 2 $$Bv\pi r^{2}/2$$ and $$P$$ is at a higher potential 3 $$\pi rvB$$ and $$R$$ is at a higher potential 4 $$2BvR$$ and $$R$$ is at higher potential
Subtopic: Â Motional emf |
Â 74%
From NCERT
AIPMT - 2014
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A coil of self-inductance $$L$$ is connected in series with a bulb $$B$$ and an AC source. The brightness of the bulb decreases when:
 1 number of turns in the coil is reduced. 2 a capacitance of reactance $$X_C = X_L$$ is included in the same circuit. 3 an iron rod is inserted in the coil. 4 frequency of the AC source is decreased.
Subtopic: Â Self - Inductance |
Â 67%
From NCERT
AIPMT - 2013
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A wire loop is rotated in a magnetic field. The frequency of change of direction of the induced emf is:
 1 twice per revolution. 2 four times per revolution. 3 six times per revolution. 4 once per revolution.

Subtopic: Â Faraday's Law & Lenz Law |
Â 74%
From NCERT
AIPMT - 2013
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A coil of resistance $$400~\Omega$$ is placed in a magnetic field. The magnetic flux $$\phi~\text{(Wb)}$$ linked with the coil varies with time $$t~\text{(s)}$$ as $$\phi=50t^{2}+4.$$ The current in the coil at $$t=2~\text{s}$$ is:
1. $$0.5~\text{A}$$
2. $$0.1~\text{A}$$
3. $$2~\text{A}$$
4. $$1~\text{A}$$

Subtopic: Â Faraday's Law & Lenz Law |
Â 88%
From NCERT
AIPMT - 2012
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The current ($$I$$) in the inductance is varying with time ($$t$$) according to the plot shown in the figure.

Which one of the following is the correct variation of voltage with time in the coil?
 1 2 3 4
Subtopic: Â Self - Inductance |
Â 73%
From NCERT
AIPMT - 2012
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The current $$i$$ in a coil varies with time as shown in the figure. The variation of induced emf with time would be:

 1 2 3 4
Subtopic: Â Faraday's Law & Lenz Law |
Â 69%
From NCERT
AIPMT - 2011
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A conducting circular loop is placed in a uniform magnetic field, $$B=0.025~\text{T}$$ with its plane perpendicular to the loop. The radius of the loop is made to shrink at a constant rate of $$1~\text{mm s}^{-1}$$. The induced emf, when the radius is $$2~\text{cm}$$, is:
1. $$2\pi ~\mu\text{V}$$
2. $$\pi ~\mu\text{V}$$
3. $$\dfrac{\pi}{2}~\mu\text{V}$$
4. $$2 ~\mu \text{V}$$

Subtopic: Â Faraday's Law & Lenz Law |
Â 76%
From NCERT
AIPMT - 2010
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A conducting circular loop is placed in a uniform magnetic field of $$0.04$$ T with its plane perpendicular to the magnetic field. The radius of the loop starts shrinking at a rate of $$2$$ mm/s. The induced emf in the loop when the radius is $$2$$ cm is:
1. $$3.2\pi ~\mu \text{V}$$

2. $$4.8\pi ~\mu\text{V}$$

3. $$0.8\pi ~\mu \text{V}$$

4. $$1.6\pi ~\mu \text{V}$$

Subtopic: Â Faraday's Law & Lenz Law |
Â 69%
From NCERT
AIPMT - 2009
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A rectangular, a square, a circular, and an elliptical loop, all in the $$(x\text-y)$$ plane, are moving out of a uniform magnetic field with a constant velocity, $$\vec{v}= v\hat{i}.$$ The magnetic field is directed along the negative $$z\text-$$axis direction. The induced emf, during the passage of these loops out of the field region, will not remain constant for:
 1 the rectangular, circular, and elliptical loops. 2 the circular and the elliptical loops. 3 only the elliptical loop. 4 any of the four loops.
Subtopic: Â Motional emf |
Â 72%
From NCERT
AIPMT - 2009
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