Explanation:
More is the intensity of incident radiation, more is the umber of photons and thus more is the number of photo electrons emitted. This results in the increase in the photo-current.
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Assertion : The electric bulbs glows immediately when switch is on.
Reason : The drift velocity of electrons in a metallic wire is very high.
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(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
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(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
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(c) If assertion is true but reason is false. |
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(d) If the assertion and reason both are false. |
A magnet is brought towards a coil (i) speedly (ii) slowly then the induced e.m.f./induced charge will be respectively
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(a) More in first case / More in first case |
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(b) More in first case/Equal in both case |
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(c) Less in first case/More in second case |
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(d) Less in first case/Equal in both case |
An electric dipole of moment p is placed at the origin along the x-axis. The electric field at a point P, whose position vector makes an angle θ with the x -axis, will make an angle ..... with the x -axis, where tanα = 
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(a) α |
(b) θ |
(c) θ + α |
(d) θ +2 α |
Which of the following statements are true regarding Bohr's model of hydrogen atom
(I) Orbiting speed of electron decreases as it shifts to discrete orbits away from the nucleus
(II) Radii of allowed orbits of electron are proportional to the principal quantum number
(III) Frequency with which electrons orbits around the nucleus in discrete orbits is inversely proportional to the principal quantum number
(IV) Binding force with which the electron is bound to the nucleus increases as it shifts to outer orbits Select correct answer using the codes given below
Codes :
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(a) I and III |
(b) II and IV |
(c) I, II and III |
(d) II, III and IV |
Find VAB
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(a) 10 V |
(b) 20 V |
(c) 30 V |
(d) None of these |
In a wire of circular cross-section with radius r, free electrons travel with a drift velocity V when a current I flows through the wire. What is the current in another wire of half the radius and of the same material when the drift velocity is 2V
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(a) 2I |
(b) I |
(c) I/2 |
(d) I/4 |
Two protons A and B are placed in space between plates of a parallel plate capacitor charged upto V volts (See fig.) Forces on protons are 
and 
, then
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(a) |
(b) |
(c) |
(d) Nothing can be said |
Faraday’s 2nd law states that mass deposited on the electrode is directly proportional to
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(a) Atomic mass |
(b) Atomic mass × Velocity |
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(c) Atomic mass/Valency |
(d) Valency |
