Explanation:
In semiconductors at room temperature the electrons get enough energy so that they are able to over come the forbidden gap. Thus at room temperature the valence band is partially empty and conduction band is partially filled.
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
A cell of e.m.f 1.5 V having a finite internal resistance is connected to a load resistance of 2Ω. For maximum power transfer the internal resistance of the cell should be
|
(a) 4 ohm |
(b) 0.5 ohm |
(c) 2 ohm |
(d) None of these |
Find the equivalent resistance across AB
|
(a) 1 W |
(b) 2 W |
(c) 3 W |
(d) 4 W |
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 |
Atomic number of a nucleus is Z and atomic mass is M. The number of neutron is
|
(a) M - Z |
(b) M |
(c) Z |
(d) M + Z |
Source of Sun's energy is
|
(a) Burning of hydrogen |
(b) Fission reactions involving hydrogen |
|
(c) Fusion reactions involving hydrogen |
(d) Some other source |
Angle between equipotential surface and lines of force is
|
(a) Zero |
(b) 180° |
(c) 90° |
(d) 45° |
When air is replaced by a dielectric medium of constant k, the maximum force of attraction between two charges separated by a distance
|
(a) Decreases k times |
(b) Remains unchanged |
|
(c) Increases k times |
(d) Increases |
If the potential of a capacitor having capacity of 6 mF is increased from 10 V to 20 V, then increase in its energy will be
|
(a) 12 × 10–6 J |
(b) 9 × 10–4 J |
(c) 4 × 10–6 J |
(d) 4 × 10–9 J |
An interference pattern was made by using red light. If the red light changes with blue light, the fringes will become
|
(a) Wider |
(b) Narrower |
(c) Fainter |
(d) Brighter |
