A sheet is placed on a horizontal surface in front of a strong magnetic pole. A force is needed to:
 $$\mathrm A.$$ hold the sheet there if it is magnetic. $$\mathrm B.$$ hold the sheet there if it is non-magnetic. $$\mathrm C.$$ move the sheet away from the pole with uniform velocity if it is conducting. $$\mathrm D.$$ move the sheet away from the pole with uniform velocity if it is both, non-conducting and non-polar.
Choose the correct statement$$(\mathrm s )$$ from the options given below:
1. $$\mathrm A$$ and $$\mathrm C$$ only
2. $$\mathrm A$$, $$\mathrm C$$ and $$\mathrm D$$ only
3. $$\mathrm C$$ only
4. $$\mathrm B$$ and $$\mathrm D$$ only
Subtopic: Â Faraday's Law & Lenz Law |
From NCERT
NEET - 2024
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An ideal inductor-resistor-battery circuit is switched on at $$t=0~\text{s}$$. At time $$t$$, the current is $$i=i_0\left(1-e^{\left(-\frac{t}{\tau}\right)}\right)\text{A}$$, where $$i_0$$ is the steady-state value. The time at which the current becomes $$0.5i_0$$ is: [Given $$\text{ln}(2)= 0.693$$]
1. $$6.93 \times 10^3 ~\text{s}$$
2. $$6.93~\text{ms}$$
3. $$69.3~\text{s}$$
4. $$6.93~\text{s}$$
Subtopic: Â LR circuit |
Â 59%
From NCERT
NEET - 2024
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A conducting circular loop of face area $$2.5 \times 10^{-3}~\text{m}^2$$ is placed perpendicular to a magnetic field which varies as $$B=0.5\sin(100 \pi t)~\text{T}$$. The magnitude of induced emf at time $$t= 0~\text{s}$$ is:
 1 $$0.125 \pi~ \text{mV}$$ 2 $$125 \pi ~\text{mV}$$ 3 $$125 \pi~\text{V}$$ 4 $$12.5 \pi~\text{mV}$$
Subtopic: Â Faraday's Law & Lenz Law |
Â 64%
From NCERT
NEET - 2024
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A rod of length $$L$$ rotates with a small uniform angular velocity $$\omega$$ about its perpendicular bisector. A uniform magnetic field $$\mathrm B$$ exists parallel to the axis of rotation. The potential difference between the centre of the rod and an end is:
1. $$\large\frac{B\omega L^2}{8}$$
2. $$\large\frac{B\omega L^2}{2}$$
3. $$\large\frac{B\omega L^2}{4}$$
4. zero
Subtopic: Â Motional emf |
From NCERT
NEET - 2024
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Let us consider two solenoids $$A$$ and $$B,$$ made from the same magnetic material of relative permeability $$\mu_{r}$$ and equal area of cross-section. Length of $$A$$ is twice that of $$B$$ and the number of turns per unit length in $$A$$ is half that of $$B.$$ The ratio of self inductances of the two solenoids, $$L_A:L_B$$ is:
1. $$1:2$$
2. $$2:1$$
3. $$8:1$$
4. $$1:8$$
Subtopic: Â Self - Inductance |
Â 55%
From NCERT
NEET - 2024
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The magnetic energy stored in an inductor of inductance $$4~\mu\text{H}$$ carrying a current of $$2~\text{A}$$ is:
1. $$8~\mu \text{J}$$
2. $$4~\mu \text{J}$$
3. $$4~\text{mJ}$$
4. $$8~\text{mJ}$$
Subtopic: Â Self - Inductance |
Â 73%
From NCERT
NEET - 2023
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An emf is generated by an ac generator having $$100$$ turn coil, of loop area $$1$$ m2. The coil rotates at a speed of one revolution per second and placed in a uniform magnetic field of $$0.05$$ T perpendicular to the axis of rotation of the coil. The maximum value of emf is:
1. $$3.14$$ V
2. $$31.4$$ V
3. $$62.8$$ V
4. $$6.28$$ V
Subtopic: Â Motional emf |
Â 71%
From NCERT
NEET - 2023
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A square loop of side $$1$$ m and resistance $$1$$ $$\Omega$$ is placed in a magnetic field of $$0.5$$ T. If the plane of the loop is perpendicular to the direction of the magnetic field, the magnetic flux through the loop is:
 1 $$0$$ 2 $$2$$ weber 3 $$0.5$$ weber 4 $$1$$ weber
Subtopic: Â Magnetic Flux |
Â 66%
From NCERT
NEET - 2022
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A big circular coil of $$1000$$ turns and average radius $$10~\text{m}$$ is rotating about its horizontal diameter at $$2~\text{rad s}^{-1}$$. If the vertical component of earth's magnetic field at that place is $$2\times 10^{-5}~\text{T}$$ and electrical resistance of the coil is $$12.56~\Omega,$$ then the maximum induced current in the coil will be:
 1 $$2~\text{A}$$ 2 $$0.25~\text{A}$$ 3 $$1.5~\text{A}$$ 4 $$1~\text{A}$$
Subtopic: Â Faraday's Law & Lenz Law |
Â 55%
From NCERT
NEET - 2022
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The current in an inductor of self-inductance $$4~\text{H}$$ changes from $$4~ \text{A}$$ to $$2~\text{A}$$ in $$1~ \text s$$. The emf induced in the coil is:
1. $$-2~\text{V}$$
2. $$2~\text{V}$$
3. $$-4~\text{V}$$
4. $$8~\text{V}$$

Subtopic: Â Self - Inductance |
Â 83%
From NCERT
NEET - 2022
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