An oil drop having charge 2e is kept stationary between two parallel horizontal plates 2.0 cm apart when a potential difference of 12000 volts is applied between them. If the density of oil is 900 kg/m3, the radius of the drop will be
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(a) 2.0 |
(b) 1.7 |
(c) 1.4 |
(d) 1.1 |
(b) 1.7 
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The reason of seeing the Sun a little before the sunrise is
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(a) Reflection of the light |
(b) Refraction of the light |
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(c) Scattering of the light |
(d) Dispersion of the light |
The energy band gap is maximum in
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(a) Metals |
(b) Superconductors |
(c) Insulators |
(d) Semiconductors |
Which of the following statement is correct
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(a) Both Peltier and Joule effects are reversible |
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(b) Both Peltier and Joule effects are irreversible |
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(c) Joule effect is reversible, whereas Peltier effect is irreversible |
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(d) Joule effect is irreversible, whereas Peltier effect is reversible |
The apparent depth of an object lying in a denser medium is always ......... than the real depth.
A battery having e.m.f. 5V and internal resistance 0.5 W is connected with a resistance of 4.5 W then the voltage at the terminals of battery is
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(a) 4.5 V |
(b) 4 V |
(c) 0 V |
(d) 2 V |
In Young’s double slit experiment, distance between two sources is 0.1 mm. The distance of screen from the sources is 20 cm. Wavelength of light used is 5460 Å. Then angular position of the first dark fringe is
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(a) 0.08° |
(b) 0.16° |
(c) 0.20° |
(d) 0.313° |
Fermi level of energy of an intrinsic semiconductor lies
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(a) In the middle of forbidden gap |
(b) Below the middle of forbidden gap |
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(c) Above the middle of forbidden gap |
(d) Outside the forbidden gap |
Which of the following is true
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(a) Lyman series is a continuous spectrum |
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(b) Paschen series is a line spectrum in the infrared |
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(c) Balmer series is a line spectrum in the ultraviolet |
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(d) The spectral series formula can be derived from the Rutherford model of the hydrogen atom |