A thin flat circular disc of radius \(4.5~\text {cm}\) is placed gently over the surface of water. If surface tension of water is \(0.07~\text{Nm}^{-1},\) then the excess force required to take it away from the surface is:
1. \(198~\text{N}\)
2. \(1.98~\text{mN}\)
3. \(99~\text{N}\)
4. \(19.8~\text{mN}\)

Subtopic:  Surface Tension |
From NCERT
NEET - 2024
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Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): The potential \((V)\) at any axial point, at \(2~\text m\)  distance (\(r\)) from the centre of the dipole of dipole moment vector \(\vec P\) of magnitude, \(4\times10^{-6}~\text{C m},\) is \(\pm9\times10^3~\text{V}.\) (Take \({\dfrac{1}{4\pi\varepsilon_0}}=9\times10^9\) SI units)
Reason (R): \(V=\pm{\dfrac{2P}{4\pi\varepsilon_0r^2}},\) where \(r\) is the distance of any axial point situated at \(2~\text m\) from the centre of the dipole.
In the light of the above statements, choose the correct answer from the options given below:
1. Both (A) and (R) are True and (R) is not the correct explanation of (A).
2. (A) is True but (R) is False.
3. (A) is False but (R) is True.
4. Both (A) and (R) are True and (R) is the correct explanation of (A).
Subtopic:  Electric Potential |
 51%
From NCERT
NEET - 2024
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In a uniform magnetic field of \(0.049~\text T\), a magnetic needle performs \(20\) complete oscillations in \(5\) seconds as shown. The moment of inertia of the needle is \(9.8 × 10^{-6} ~\text{kg m}^2\). If the magnitude of magnetic moment of the needle is \(x \times 10^{-5 }~\text {Am}^2;\) then the value of '\(x\)' is:
                
1. \(128\pi^2\)
2.  \(50\pi^2\)
3. \(1280\pi^2\)
4. \(5\pi^2\)
Subtopic:  Bar Magnet |
From NCERT
NEET - 2024
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If the monochromatic source in Young's double slit experiment is replaced by white light, then:
1. there will be a central dark fringe surrounded by a few coloured fringes.
2. there will be a central bright white fringe surrounded by a few coloured fringes.
3. all bright fringes will be of equal width.
4. interference pattern will disappear.
Subtopic:  Young's Double Slit Experiment |
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From NCERT
NEET - 2024
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Given below are two statements:
Statement I: Atoms are electrically neutral as they contain equal number of positive and negative charges.
Statement II: Atoms of each element are stable and emit their characteristic spectrum.
 
In the light of the above statements, choose the most appropriate answer from the options given below:
1. Both Statement I and Statement II are incorrect.
2. Statement I is correct but Statement II is incorrect.
3. Statement I is incorrect but Statement II is correct.
4. Both Statement I and Statement II are correct.
Subtopic:  Spectral Series |
From NCERT
NEET - 2024
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The maximum elongation of a steel wire of \(1~\text m\) length if the elastic limit of steel and its Young's modulus, respectively, are \(8 × 10^8 ~\text{N m}^{-2 }\) and \(2 × 10^{11} ~\text{N m}^{-2},\) is:
1. \(0.4~\text{mm}\)
2. \(40~\text{mm}\)
3. \(8~\text{mm}\)
4. \(4~\text{mm}\)
Subtopic:  Young's modulus |
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From NCERT
NEET - 2024
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Consider the following Statements A and B and identify the correct answer:
                   
A. For a solar-cell, the \(I\text-V\) characteristics lies in the IV quadrant of the given graph.
B. In a reverse-biased pn junction diode, the current measured in (\(\mu \text{A}\)), is due to majority charge carriers.
 
1. A is incorrect but B is correct.
2. Both A and B are correct.
3. Both A and B are incorrect.
4. A is correct but B is incorrect.
Subtopic:  Applications of PN junction |
From NCERT
NEET - 2024
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A particle moving with uniform speed in a circular path maintains:
1. constant acceleration.
2. constant velocity but varying acceleration.
3. varying velocity and varying acceleration.
4. constant velocity.
Subtopic:  Circular Motion |
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From NCERT
NEET - 2024
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If \(c\) is the velocity of light in free space, the correct statements about photon among the following are:
A. The energy of a photon is \(E=h\nu.\)
B. The velocity of a photon is \(c.\)
C. The momentum of a photon, \(p={\dfrac{h\nu}{c}}.\)
D. In a photon-electron collision, both total energy and total momentum are conserved.
E. Photon possesses positive charge.
Choose the correct answer from the options given below:
1. \(\text {A, B, C}\) and \(\text {D}\) only
2. \(\text {A, C}\) and \(\text {D}\) only
3. \(\text {A, B, D}\) and \(\text {E}\) only
4. \(\text {A}\) and \(\text {B}\) only
Subtopic:  Particle Nature of Light |
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From NCERT
NEET - 2024
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Two bodies \(A\) and \(B\) of same mass undergo completely inelastic one dimensional collision. The body \(A\) moves with velocity \(v_1\) while body \(B\) is at rest before collision. The velocity of the system after collision is \(v_2\). The ratio \(v_1:v_2\) is:
1. \(2:1\)
2. \(4:1\)
3. \(1:4\)
4. \(1:2\)
Subtopic:  Collisions |
 62%
From NCERT
NEET - 2024
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