Select the correct statement
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(a) In a full wave rectifier, two diodes work alternately |
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(b) In a full wave rectifier, two diodes work simultaneously |
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(c) The efficiency of full wave and half wave rectifiers is same |
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(d) The full wave rectifier is bi-directional. |
(a) In a full wave rectifier, two diodes work alternately
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Red light is generally used to observe diffraction pattern from single slit. If blue light is used instead of red light, then diffraction pattern
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(a) Will be more clear |
(b) Will contract |
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(c) Will expanded |
(d) Will not be visualized |
A concave lens of glass, refractive index 1.5, has both surfaces of same radius of curvature R. On immersion in a medium of refractive index 1.75, it will behave as a
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(a) Convergent lens of focal length 3.5 R |
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(b) Convergent lens of focal length 3.0 R |
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(c) Divergent lens of focal length 3.5 R |
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(d) Divergent lens of focal length 3.0 R |
Certain radio-active substance reduces to 25% of its value in 16 days. Its half-life is
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(a) 32 days |
(b) 8 days |
(c) 64 days |
(d) 28 days |
Assertion : In the following circuit emf is 2V and internal resistance of the cell is 1 W and R = 1W, then reading of the voltmeter is 1V.
Reason : V = E - ir where E = 2V, i = 
and R = 1 W
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(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
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(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
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(c) If assertion is true but reason is false. |
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(d) If the assertion and reason both are false. |
The expression for thermo e.m.f. in a thermocouple is given by the relation E = 40 θ - 
, where θ is the temperature difference of two junctions. For this, the neutral temperature will be
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(a) 100℃ |
(b) 200℃ |
(c) 300℃ |
(d) 400℃ |
An ammeter and a voltmeter of resistance R are connected in series to an electric cell of negligible internal resistance. Their readings are A and V respectively. If another resistance R is connected in parallel with the voltmeter
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(a) Both A and V will increase |
(b) Both A and V will decrease |
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(c) A will decrease and V will increase |
(d) A will increase and V will decrease |
In the spectrum of light of a luminous heavenly body the wavelength of a spectral line is measured to be 4747 Å while actual wavelength of the line is 4700 Å. The relative velocity of the heavenly body with respect to earth will be (velocity of light is 3
)
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(a) 3 |
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(b) 3 |
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(c) 3 |
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(d) 3 |
