The average e.m.f. induced in a coil in which a current changes from 0 to 2 A in 0.05 s is 8 V. The self inductance of the coil is
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(a) 0.1 H |
(b) 0.2 H |
(c) 0.4 H |
(d) 0.8 H |
(b) 0.2 H
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The charge on electron was discovered by
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(a) J.J. Thomson |
(b) Neil Bohr |
(c) Millikan |
(d) Chadwick |
The cyclotron frequency of an electron grating in a magnetic field of 1 T is approximately
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(a) 28 MHz |
(b) 280 MHz |
(c) 2.8 GHz |
(d) 28 GHz |
The energy band gap of Si is
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(a) 0.70 eV |
(b) 1.1 eV |
|
(c) Between 0.70 eV to 1.1 eV |
(d) 5 eV |
An α -particle is accelerated through a potential difference of 200V. The increase in its kinetic energy is
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(a) 100 eV |
(b) 200 eV |
(c) 400 eV |
(d) 800 eV |
The coil of dynamo is rotating in a magnetic field. The developed induced e.m.f. changes and the number of magnetic lines of force also changes. Which of the following condition is correct
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(a) Lines of force minimum but induced e.m.f. is zero |
|
(b) Lines of force maximum but induced e.m.f. is zero |
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(c) Lines of force maximum but induced e.m.f. is not zero |
|
(d) Lines of force maximum but induced e.m.f. is also maximum |
Choose the correct statement
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(a) When we heat a semiconductor its resistance increases |
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(b) When we heat a semiconductor its resistance decreases |
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(c) When we cool a semiconductor to 0 K then it becomes super conductor |
|
(d) Resistance of a semiconductor is independent of temperature |