Two galvanometers A and B require 3mA and 5mA respectively to produce the same deflection of 10 divisions. Then
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(a) A is more sensitive than B |
(b) B is more sensitive than A |
|
(c) A and B are equally sensitive |
(d) Sensitiveness of B is 5/3 times that of A |
(a) A is more sensitive than B
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If m1 and m2 are the refractive indices of the materials of core and cladding of an optical fibre, then the loss of light due to its leakage can be minimised by having
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(a) m1 > m2 |
(b) m1 < m2 |
(c) m1 = m2 |
(d) None of these |
Ray optics is valid, when characteristic dimensions are
|
(a) Of the same order as the wavelength of light |
|
(b) Much smaller than the wavelength of light |
|
(c) Of the order of one millimetre |
|
(d) Much larger than the wavelength of light |
The decay constant of a radioactive element is 0.01 per second. Its half life period is
|
(a) 693 sec |
(b) 6.93 sec |
(c) 0.693 sec |
(d) 69.3 sec |
An electron enters a region where magnetic (B) and electric (E) fields are mutually perpendicular to one another, then
|
(a) It will always move in the direction of B |
|
(b) It will always move in the direction of E |
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(c) It always possess circular motion |
|
(d) It can go undeflected also |
Two wires ‘A’ and ‘B’ of the same material have their lengths in the ratio 1 : 2 and radii in the ratio 2 : 1. The two wires are connected in parallel across a battery. The ratio of the heat produced in ‘A’ to the heat produced in ‘B’ for the same time is
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(a) 1 : 2 |
(b) 2 : 1 |
(c) 1 : 8 |
(d) 8 : 1 |
Assuming that universe is expanding, if the spectrum of light coming from a star which is going away from earth is tested, then in the wavelength of light
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(a) There will be no change |
|
(b) The spectrum will move to infrared region |
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(c) The spectrum will seems to shift to ultraviolet side |
|
(d) None of the above |
The magnetic field due to the earth is closely equivalent to that due to
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(a) A large magnet of length equal to the diameter of the earth |
| (b) A magnetic dipole placed at the centre of the earth |
| (c) A large coil carrying current |
| (d) Neither of the above |
In the circuit shown in figure, the heat produced in 5 ohm resistance is 10 calories per second. The heat produced in 4 resistance is
|
(a) 1 cal / sec |
(b) 2 cal/sec |
(c) 3 cal / sec |
(d) 4 cal/sec |
Which of the following is true
|
(a) Common base transistor is commonly used because current gain is maximum |
|
(b) Common emitter is commonly used because current gain is maximum |
|
(c) Common collector is commonly used because current gain is maximum |
|
(d) Common emitter is the least used transistor |