The outer sphere of a spherical air capacitor is earthed. For increasing its capacitance
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(a) Vacuum is created between two spheres |
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(b) Dielectric material is filled between the two spheres |
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(c) The space between two spheres is increased |
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(d) The earthing of the outer sphere is removed |
(b) Dielectric material is filled between the two spheres
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At a place the value of horizontal component of the earth's magnetic field H is 3
. A metallic rod AB of length 2 m placed in east-west direction, having the end A towards east, falls vertically downward with a constant velocity of 50 m/s. Which end of the rod becomes positively charged and what is the value of induced potential difference between the two ends
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(a) End A, 3 |
(b) End A, 3 mV |
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(c) End B, 3 |
(d) End B, 3 mV |
Which of the following quantities increase when wavelength is increased? Consider only the magnitudes.
Polarised glass is used in sun glasses because
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(a) It reduces the light intensity to half an account of polarisation |
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(b) It is fashionable |
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(c) It has good colour |
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(d) It is cheaper |
Electromotive force is the force, which is able to maintain a constant
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(a) Current |
(b) Resistance |
(c) Power |
(d) Potential difference |
The electron mobility in N-type germanium is 3900 cm2/v-s and its conductivity is 6.24 mho/cm, then impurity concentration will be if the effect of cotters is negligible
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(a) 1015 cm3 |
(b) 1013 /cm3 |
(c) 1012 /cm3 |
(d) 1016 /cm3 |
Consider a radioactive material of half-life 1.0 minute. If one of the nuclei decays now, the next one will decay
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(a) After 1 minute |
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(b) After |
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(c) After |
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(d) After any time |
