In a PNP transistor working as a common-base amplifier, current gain is 0.96 and emitter current is 7.2 mA. The base current is
|
(a) 0.4 mA |
(b) 0.2 mA |
(c) 0.29 mA |
(d) 0.35 mA |
(c) 0.29 mA
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In order to increase the sensitivity of a moving coil galvanometer, one should decrease
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(a) The strength of its magnet |
(b) The torsional constant of its suspension |
|
(c) The number of turns in its coil |
(d) The area of its coil |
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. |
Assertion : In high latitude one sees colourful curtains of light hanging down from high altitudes.
Reason : The high energy charged particles from the sun are deflected to polar regions by the magnetic field of the earth.
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(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. |
A point source of light is placed in front of a plane mirror:
A rod of a certain metal is 1.0 m long and 0.6 cm in diameter. Its resistance is 3.0 × 
ohm. Another disc made of the same metal is 2.0 cm in diameter and 1.0 mm thick. What is the resistance between the round faces of the disc
|
(a) 1.35 × |
(b) 2.70 × |
(c) 4.05 × |
(d) 8.10 × |
In a vibration magnetometer, the time period of a bar magnet oscillating in horizontal component of earth's magnetic field is 2 sec. When a magnet is brought near and parallel to it, the time period reduces to 1 sec. The ratio H/F of the horizontal component H and the field F due to magnet will be
| (a) 3 | (b) 1/3 |
(c) 
|
(d) 1/
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