- AIncreases potential barrier.
- BCancels the potential barrier.
- CIs equal to 1.5volt.
- DNone of these.
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To obtain electrons as majority charge carriers in a semiconductor, the impurity mixed is
|
(a) Monovalent |
(b) Divalent |
(c) Trivalent |
(d) Pentavalent |
The number of wavelengths in the visible spectrum
|
(a) 4000 |
(b) 6000 |
(c) 2000 |
(d) Infinite |
The critical angle between an equilateral prism and air is 45°. If the incident ray is perpendicular to the refracting surface, then
|
(a) After deviation it will emerge from the second refracting surface |
|
(b) It is totally reflected on the second surface and emerges out perpendicularly from third surface in air |
|
(c) It is totally reflected from the second and third refracting surfaces and finally emerges out from the first surface |
|
(d) It is totally reflected from all the three sides of prism and never emerges out |
A long solenoid has 200 turns per cm and carries a current of 2.5 amps. The magnetic field at its centre is (![]()
|
(a) 3.14 |
(b) 6.28 |
|
(c) 9.42 |
(d) 12.56 |
Between the primary and secondary rainbows, there is a dark band known as Alexandar’s dark band. This is because: