- APhotoelectrons absorb and emit photons
- BThe velocity of light is the same for all observers
- CMass and energy are intra- convertible
- DEnergy and momentum are conserved
Explanation:
The main postulate of Einstein's special theory of relativity is that the speed of light is constant and equal to c in all the inertial frames i.e the velocity of light is same for all observers.
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The emitter-base junction of a transistor is …… biased while the collector-base junction is ……. biased
|
(a) Reverse, forward |
(b) Reverse, reverse |
(c) Forward, forward |
(d) Forward, reverse |
The photoelectric threshold wavelength for potassium (work function being 2eV ) is
|
(a) 310 nm |
(b) 620 nm |
(c) 1200 nm |
(d) 2100 nm |
The first excited state of hydrogen atom is 10.2 eV above its ground state. The temperature is needed to excite hydrogen atoms to first excited level, is
|
(a) 7.9 |
(b) 3.5 |
(c) 5.8 |
(d) 14 |
What is the net force on a Cl– placed at the centre of the bcc structure of CsCl

|
(a) Zero |
(b) |
(c) |
(d) Data is incomplete |
A transistor is used as an amplifier in CB mode with a load resistance of 5 k W the current gain of amplifier is 0.98 and the input resistance is 70 W, the voltage gain and power gain respectively are
|
(a) 70, 68.6 |
(b) 80, 75.6 |
(c) 60, 66.6 |
(d) 90, 96.6 |
The a-particle is the nucleus of an atom of
|
(a) Neon |
(b) Hydrogen |
(c) Helium |
(d) Deuterium |
A current of 2 A passing through conductor produces 80 J of heat in 10 seconds. The resistance of the conductor is
|
(a) 0.5 Ω |
(b) 2 Ω |
(c) 4 Ω |
(d) 20 Ω |