If the thermionic current density is J and emitter temperature is T then the curve between 
and 
will be
(a)
|
(b)
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(c)
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(d)
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A voltmeter essentially consists of
|
(a) A high resistance, in series with a galvanometer |
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(b) A low resistance, in series with a galvanometer |
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(c) A high resistance in parallel with a galvanometer |
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(d) A low resistance in parallel with a galvanometer |
Metallic solids are always opaque because
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(a) Solids effect the incident light |
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(b) Incident light is readily absorbed by the free electron in a metal |
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(c) Incident light is scattered by solid molecules |
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(d) Energy band traps the incident light |
Assertion : A parallel plate capacitor is connected across battery through a key. A dielectric slab of constant K is introduced between the plates. The energy which is stored becomes K times.
Reason : The surface density of charge on the plate remains constant or unchanged.
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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 area of each plate of a parallel plate capacitor is 
and the distance between the plates is 1mm. It is filled with mica of dielectric 6. The radius of the equivalent capacity of the sphere will be
|
(a) 47.7 m |
(b) 4.77 m |
(c) 477 m |
(d) None of the above |
A potential difference of 2V is applied between the opposite faces of a Ge crystal plate of area 1 cm2 and thickness 0.5 mm. If the concentration of electrons in Ge is 2 × 1019/m3 and mobilities of electrons and holes are 0.36 
and 0.14 respectively, then the current flowing through the plate will be
|
(a) 0.25 A |
(b) 0.45 A |
(c) 0.56 A |
(d) 0.64 A |
A photon in motion has a mass
|
(a) c/hv |
(b) h/v |
(c) hv |
(d) |
