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The phenomenon by which light travels in an optical fibres is
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(a) Reflection |
(b) Refraction |
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(c) Total internal reflection |
(d) Transmission |
If 96500 coulombs of electricity liberates one gram equivalent of any substance, the time taken for a current of 0.15 amperes to deposite 20mg of copper from a solution of copper sulphate is (Chemical equivalent of copper = 32)
|
(a) 5 min 20 sec |
(b) 6 min 42 sec |
(c) 4 min 40 sec |
(d) 5 min 50 sec |
The figure below shows the north and south poles of a permanent magnet in which n turn coil of area of cross-section A is resting, such that for a current i passed through the coil, the plane of the coil makes an angle θ with respect to the direction of magnetic field B. If the plane of the magnetic field and the coil are horizontal and vertical respectively, the torque on the coil will be
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(a) τ = niAB cosθ |
|
(b) τ = niAB sinθ |
|
(c) τ = niAB |
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(d) None of the above, since the magnetic field is radial |
A battery of e.m.f. 10 V and internal resistance 0.5 ohm is connected across a variable resistance R. The value of R for which the power delivered in it is maximum is given by
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(a) 2.0 ohm |
(b) 0.25 ohm |
(c) 1.0 ohm |
(d) 0.5 ohm |
An AIR station is broadcasting the waves of wavelength 300 metres. If the radiating power of the transmitter is 10 kW, then the number of photons radiated per second is
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(a) 1.5 |
(b) 1.5 |
(c) 1.5 |
(d) 1.5 |
