If $$\oint_s \vec{E} \cdot \overrightarrow{d S}=0$$ over a surface, then:   1. the electric field inside the surface is necessarily uniform. 2. the number of flux lines entering the surface must be equal to the number of flux lines leaving it. 3. the magnitude of electric field on the surface is constant. 4. all the charges must necessarily be inside the surface.

Subtopic:  Gauss's Law |
78%
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NEET - 2023
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Given below are two statements:
 Statement I: Photovoltaic devices can convert optical radiation into electricity. Statement II: Zener diode is designed to operate under reverse bias in the breakdown.
 1 Statement I is incorrect but Statement II is correct. 2 Both Statement I and Statement II are correct. 3 Both Statement I and Statement II are incorrect. 4 Statement I is correct but Statement II is incorrect.
Subtopic:  Applications of PN junction |
74%
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NEET - 2023
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In a plane electromagnetic wave travelling in free space, the electric field component oscillates sinusoidally at a frequency of $$2.0\times 10^{10}~ \text{Hz}$$ and amplitude $$48~\text{Vm}^{-1}$$. Then the amplitude of the oscillating magnetic field is: (Speed of light in free space $$3\times 10^{8}~ \text{ms}^{-1}$$)
1. $$1.6 \times 10^{-6} ~\text{T}$$
2. $$1.6 \times 10^{-9} ~\text{T}$$
3. $$1.6 \times 10^{-8} ~\text{T}$$
4. $$1.6 \times 10^{-7} ~\text{T}$$
Subtopic:  Properties of EM Waves |
58%
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NEET - 2023
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The temperature of a gas is $$-50^\circ \text{C}$$. To what temperature the gas should be heated so that the rms speed is increased by $$3$$ times?
 1 $$223~\text{K}$$ 2 $$669^\circ \text{C}$$ 3 $$3295^\circ \text{C}$$ 4 $$3097~\text{K}$$
Subtopic:  Types of Velocities |
51%
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NEET - 2023
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The magnitude and direction of the current in the following circuit is:
 1 $$1.5~\text{A}$$ from $$\mathrm{B}$$ to $$\mathrm{A}$$ through $$E$$ 2 $$0.2~\text{A}$$ from $$\mathrm{B}$$ to $$\mathrm{A}$$ through $$E$$ 3 $$0.5~\text{A}$$  from $$\mathrm{A}$$ to $$\mathrm{B}$$ through $$E$$ 4 $$\dfrac{5}{9}~\text{A}$$ from $$\mathrm{A}$$ to $$\mathrm{B}$$ through $$E$$
Subtopic:  Kirchoff's Voltage Law |
70%
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NEET - 2023
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An electric dipole is placed at an angle of $$30^\circ$$ with an electric field of intensity $$2\times 10^5 ~\text{NC}^{-1}$$. It experiences a torque equal to $$4~\text{N-m}$$. Calculate the magnitude of charge on the dipole if the dipole length is $$2~\text{cm}$$.
1. $$2~\text{mC}$$
2. $$8~\text{mC}$$
3. $$6~\text{mC}$$
4. $$4~\text{mC}$$
Subtopic:  Electric Dipole |
71%
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NEET - 2023
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Let a wire be suspended from the ceiling (rigid support) and stretched by a weight $$W$$ attached at its free end. The longitudinal stress at any point of cross-sectional area $$A$$ of the wire is:
1. zero
2. $$\dfrac{2W}{A}$$
3. $$\dfrac{W}{A}$$
4. $$\dfrac{W}{2A}$$
Subtopic:  Stress - Strain |
65%
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NEET - 2023
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The equivalent capacitance of the system shown in the following circuit is:

1. $$9~{\mu \text{F}}$$
2. $$2~{\mu \text{F}}$$
3. $$3~{\mu \text{F}}$$
4. $$6~{\mu \text{F}}$$
Subtopic:  Combination of Capacitors |
78%
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NEET - 2023
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The venturi-meter works on:
 1 The principle of perpendicular axes 2 Huygen's principle 3 Bernoulli's principle 4 The principle of parallel axes
Subtopic:  Bernoulli's Theorem |
81%
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NEET - 2023
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$$12~\text{V},60~\text{W}$$ lamp is connected to the secondary of a step down transformer, whose primary is connected to ac mains of $$220~\text{V}$$. Assuming the transformer to be ideal, what is the current in the primary winding?
1. $$0.37~\text{A}$$
2. $$0.27~\text{A}$$
3. $$2.7~\text{A}$$
4. $$3.7~\text{A}$$
Subtopic:  Transformer |
68%
From NCERT
NEET - 2023