A photocell is illuminated by a small bright source placed 1 m away. When the same source of light is placed 
away, the number of electrons emitted by photo cathode would
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(a) Decrease by a factor of 2 |
(b) Increase by a factor of 2 |
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(c) Decrease by a factor of 4 |
(d) Increase by a factor of 4 |
(d) Increase by a factor of 4
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Young's experiment establishes that
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(a) Light consists of waves |
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(b) Light consists of particles |
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(c) Light consists of neither particles nor waves |
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(d) Light consists of both particles and waves |
Assertion : The magnetic filed at the ends of a very long current carrying solenoid is half of that at the center.
Reason : If the solenoid is sufficiently long, the field within it is uniform.
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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 transconductance of a triode amplifier is 2.5 mili mho having plate resistance of 20 KW, amplification 10. Find the load resistance
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(a) 5 kW |
(b) 25 kW |
(c) 20 kW |
(d) 50 kW |
A diver in a swimming pool wants to signal his distress to a person lying on the edge of the pool by flashing his water proof flash light
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(a) He must direct the beam vertically upwards |
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(b) He has to direct the beam horizontally |
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(c) He has to direct the beam at an angle to the vertical which is slightly less than the critical angle of incidence for total internal reflection |
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(d) He has to direct the beam at an angle to the vertical which is slightly more than the critical angle of incidence for the total internal reflection |
Before the saturation state of a diode at the plate voltages of 400 V and 200 V respectively the currents are i1 and i2 respectively. The ratio i1/i2 will be
(a) 
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(b) 2
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(c) 2 | (d) 1/2 |