While a collector to emitter voltage is constant in a transistor, the collector current changes by 8.2 mA when the emitter current changes by 8.3 mA. The value of forward current ratio hfe is
|
(a) 82 |
(b) 83 |
(c) 8.2 |
(d) 8.3 |
(a) 82
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A potentiometer has uniform potential gradient across it. Two cells connected in series (i) to support each other and (ii) to oppose each other are balanced over 6m and 2m respectively on the potentiometer wire. The e.m.f.’s of the cells are in the ratio of
|
(a) 1 : 2 |
(b) 1 : 1 |
(c) 3 : 1 |
(d) 2 : 1 |
The bottom of a container filled with liquid appear slightly raised because of
|
(a) Refraction |
(b) Interference |
(c) Diffraction |
(d) Reflection |
The phenomenon of radioactivity is
|
(a) Exothermic change which increases or decreases with temperature |
|
(b) Increases on applied pressure |
|
(c) Nuclear process does not depend on external factors |
|
(d) None of the above |
Two small conducting spheres of equal radius have charges +10Μc and -20 μC respectively and placed at a distance R from each other experience force 
. If they are brought in contact and separated to the same distance, they experience force 
. The ratio of to is
|
(a) 1 : 8 |
(b) – 8 : 1 |
(c) 1 : 2 |
(d) – 2 : 1 |
A positively charged ball hangs from a silk thread. We put a positive test charge 
at a point and measure F/, then it can be predicted that the electric field strength E
|
(a) |
(b) |
(c) |
(d) Cannot be estimated |
