For a transistor, the current amplification factor is 0.8. The transistor is connected in common emitter configuration. The change in the collector current when the base current changes by 6 mA is
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(a) 6 mA |
(b) 4.8 mA |
(c) 24 mA |
(d) 8 mA |
(c) 24 mA
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Assertion : A paramagnetic sample display greater magnetisation (for the same magnetising field) when cooled.
Reason : The magnetisation does not depend on temperature.
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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 heat generated through 2 ohm and 8 ohm resistances separately, when a condenser of 200 μF capacity charged to 200 V is discharged one by one, will be
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(a) 4 J and 16 J respectively |
(b) 16 J and 4 J respectively |
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(c) 4 J and 8 J respectively |
(d) 4 J and 4 J respectively |
A light source approaches the observer with velocity 0.8 c. The doppler shift for the light of wavelength 5500 Å is
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(a) 4400 Å |
(b) 1833 Å |
(c) 3167 Å |
(d) 7333 Å |
An image of the sun is formed by a lens of focal length of 30 cm on the metal surface of a photoelectric cell and a photoelectric current I is produced. The lens forming the image is then replaced by another of the same diameter but of focal length 15 cm. The photoelectric current in this case is
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(a) |
(b) I |
(c) 2I |
(d) 4I |
An electric dipole is kept in non-uniform electric field. It experiences
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(a) A force and a torque |
(b) A force but not a torque |
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(c) A torque but not a force |
(d) Neither a force nor a torque |
