In a full wave rectifiers, input ac current has a frequency ‘n’. The output frequency of current is
|
(a) n/2 |
(b) n |
(c) 2n |
(d) None of these |
(c) 2n
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The amplification factor of a triode is 50. If the grid potential is decreased by 0.20 V, what increase in plate potential will keep the plate current unchanged
|
(a) 5 V |
(b) 10 V |
(c) 0.2 V |
(d) 50 V |
In good conductors of electricity, the type of bonding that exists is
|
(a) Ionic |
(b) Vander Waals |
(c) Covalent |
(d) Metallic |
A prism (μ = 1.5) has the refracting angle of 30°. The deviation of a monochromatic ray incident normally on its one surface will be (sin 48° 36’ = 0.75)
|
(a) 18° 36’ |
(b) 20° 30’ |
(c) 18° |
(d) 22°1’ |
The work function for tungsten and sodium are 4.5 eV and 2.3 eV respectively. If the threshold wavelength λ for sodium is 
, the value of λ for tungsten is
|
(a) 5893 Å |
(b) 10683 Å |
(c) 2791 Å |
(d) 528 Å |
Two short magnets placed along the same axis with their like poles facing each other repel each other with a force which varies inversely as
| (a) Square of the distance | (b) Cube of the distance |
| (c) Distance | (d) Fourth power of the distance |
Assertion : A metal piece and a non-metal (stone) piece are dropped from the same height near earth’s surface. Both will reach the earth’s surface simultaneously.
Reason : There is no effect of earth’s magnetic field on freely falling body.
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If the assertion and reason both are false. |
Compton effect shows that
|
(a) X-rays are waves |
(b) X-rays have high energy |
|
(c) X-rays can penetrate matter |
(d) Photons have momentum |