# The potential energy of a long spring when stretched by $$2$$ cm is $$U$$. If the spring is stretched by $$8$$ cm, potential energy stored in it will be:  1. $$16U$$ 2. $$2U$$ 3. $$4U$$ 4. $$8U$$

Subtopic:  Elastic Potential Energy |
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A bullet is fired from a gun at the speed of $$280$$ ms–1 in the direction $$30^\circ$$ above the horizontal. The maximum height attained by the bullet is: ($$g=9.8$$ ms–2, $$\mathrm{sin}30^{0}=0.5$$ )
 1 $$3000$$ m 2 $$2800$$ m 3 $$2000$$ m 4 $$1000$$ m
Subtopic:  Projectile Motion |
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The half-life of a radioactive substance is $$20$$ minutes. In how much time, the activity of substance drops to $$(\frac{1}{16})^{\mathrm{th}}$$ of its initial value?
1. $$80$$ minutes
2. $$20$$ minutes
3. $$40$$ minutes
4. $$60$$ minutes
Subtopic:  Radioactivity (OLD NCERT) |
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The net magnetic flux through any closed surface is:
1. negative
2. zero
3. positive
4. infinity
Subtopic:  Analogy between Electrostatics & Magnetostatics |
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A metal wire has mass $$(0.4\pm 0.002)~\mathrm{g}$$, radius $$(0.3\pm 0.001)~\mathrm{mm}$$ and length $$(5\pm 0.02)~\mathrm{cm}$$. The maximum possible percentage error in the measurement of density will nearly be:
1. $$1.4 \%$$
2. $$1.2 \%$$
3. $$1.3 \%$$
4. $$1.6 \%$$
Subtopic:  Errors |
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NEET - 2023
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The angular acceleration of a body, moving along the circumference of a circle, is:
 1 along the axis of rotation 2 along the radius, away from centre 3 along the radius towards the centre 4 along the tangent to its position
Subtopic:  Rotational Motion: Kinematics |
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The magnetic energy stored in an inductor of inductance $$4~\mathrm{\mu H}$$ carrying a current of $$2~\text{A}$$ is:
1. $$8~\mathrm{\mu J}$$
2. $$4~\mathrm{\mu J}$$
3. $$4~\mathrm{mJ}$$
4. $$8~\mathrm{mJ}$$
Subtopic:  Self - Inductance |
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A full wave rectifier circuit consists of two $$\mathrm{p\text-n}$$ junction diodes, a centre-tapped transformer, capacitor and a load resistance. Which of these components remove the ac ripple from the rectified output?
 1 load resistance 2 a centre-tapped transformer 3 $$\mathrm{p\text-n}$$ junction diodes 4 capacitor
Subtopic:  Rectifier |
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A football player is moving southward and suddenly turns eastward with the same speed to avoid an opponent. The force that acts on the player while turning is:
 1 along south-west 2 along eastward 3 along northward 4 along north-east
Subtopic:  Newton's Laws |
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The work functions of Caesium $$(\mathrm{Cs})$$, Potassium $$(\mathrm{K})$$ and Sodium $$(\mathrm{Na})$$ are $$2.14~\text{eV}$$, $$2.30~\text{eV}$$ and $$2.75~\text{eV}$$ respectively. If incident electromagnetic radiation has an incident energy of $$2.20~\text{eV}$$. which of these photosensitive surfaces may emit photoelectrons?
 1 $$\mathrm{Na}$$ only 2 $$\mathrm{Cs}$$ only 3 Both $$\mathrm{Na}$$ and $$\mathrm{K}$$ 4 $$\mathrm{K}$$ only
Subtopic:  Photoelectric Effect: Experiment |
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NEET - 2023
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