A constant current i is passed through a resistor. Taking the temperature coefficient of resistance into account, indicate which of the plots shown in figure best represents the rate of production of thermal energy in the resistor
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(a) a |
(b) b |
(c) c |
(d) d |
(d) d
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Assertion : Bending a wire does not effect electrical resistance.
Reason : Resistance of wire is proportional to resistivity of material.
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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. |
If the angles of dip at two places are 30o and 45o respectively, then the ratio of horizontal components of earth's magnetic field at the two places will be
(a) 
|
(b) 1 : 
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(c) 1 : 
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(d) 1 : 2 |
Two short magnets with their axes horizontal and perpendicular to the magnetic meridian are placed with their centres 40 cm east and 50 cm west of magnetic needle. If the needle remains undeflected, the ratio of their magnetic moments 
is
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(a) 4 : 5 |
(b) 16 : 25 |
(c) 64 : 125 |
(d) 2 : |
The valence of the impurity atom that is to be added to germanium crystal so as to make it a N-type semiconductor, is
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(a) 6 |
(b) 5 |
(c) 4 |
(d) 3 |
