- AThe presence of electrons
- BThe presence of holes
- CThe presence of both electrons and holes
- DNone of the above
Explanation:
In the valence band, current is only due to holes. In the conduction band, current is due to electrons.
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Two heater wires of equal length are first connected in series and then in parallel. The ratio of heat produced in the two cases is
|
(a) 2 : 1 |
(b) 1 : 2 |
(c) 4 : 1 |
(d) 1 : 4 |
The V-i graph for a conductor at temperature and
are as shown in the figure. (
is proportional to
|
(a) cos2θ |
(b) sin θ |
(c) cot 2θ |
(d) tan θ |
Which of the planet is brightest
|
(a) Mercury |
(b) Venus |
(c) Mars |
(d) Jupiter |
Gases begin to conduct electricity at low pressure because
|
(a) At low pressure, gases turn to plasma |
|
(b) Colliding electrons can acquire higher kinetic energy due to increased mean free path leading to ionisation of atoms |
|
(c) Atoms break up into electrons and protons |
|
(d) The electrons in atoms can move freely at low pressure |
A polariser is used to
|
(a) Reduce intensity of light |
(b) Produce polarised light |
|
(c) Increase intensity of light |
(d) Produce unpolarised light |
The phenomenon of diffraction of light was discovered by
|
(a) Hygens |
(b) Newton |
(c) Fresnel |
(d) Grimaldi |
To deposit one gm equivalent of an element at an electrode, the quantity of electricity needed is
|
(a) One ampere |
(b) 96000 amperes |
(c) 96500 farads |
(d) 96500 coulombs |