- AAn anti-particle of electron.
- BA vacancy created when an electron leaves a covalent bond.
- CAbsence of free electrons.
- DAn artifically created particle.
Solution:
Concept of holes in the semiconductor:
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If the momentum of a photon is p, then its frequency is (Where m is the rest mass of the photon)
|
(a) |
(b) |
(c) |
(d) |
Two conducting spheres of radii 5 cm and 10 cm are given a charge of 15 μC each. After the two spheres are joined by a conducting wire, the charge on the smaller sphere is
|
(a) 5 μC |
(b) 10 μC |
(c) 15 μC |
(d) 20 μC |
An electron (mass = 9 × 10–31kg. Charge = 1.6 × 10–19C) whose kinetic energy is 7.2 × 10–18 joule is moving in a circular orbit in a magnetic field of 9 × 10–5 weber/m2. The radius of the orbit is
|
(a) 1.25 cm |
(b) 2.5 cm |
(c) 12.5 cm |
(d) 25.0 cm |
A beam of parallel rays is brought to a focus by a plano-convex lens. A thin concave lens of the same focal length is joined to the first lens. The effect of this is
|
(a) The focal point shifts away from the lens by a small distance |
|
(b) The focus remains undisturbed |
|
(c) The focus shifts to infinity |
|
(d) The focal point shifts towards the lens by a small distance |
Which of the planet is brightest
|
(a) Mercury |
(b) Venus |
(c) Mars |
(d) Jupiter |
When a copper voltameter is connected with a battery of e.m.f. 12 volts. 2 gms of copper is deposited in 30 minutes. If the same voltameter is connected across a 6 volt battery, then the mass of copper deposited in 45 minutes would be
|
(a) 1 gm |
(b) 1.5 gm |
(c) 2 gm |
(d) 2.5 gm |
The stopping potential (
versus frequency (n) plot of a substance is shown in figure the threshold wave length is

|
(a) 5 |
(b) 6000Å |
|
(c) 5000 Å |
(d) Can not be estimated from given data |
The resistance of a wire is per metre. It is bend in the form of a circle of diameter 2 m. A wire of the same material is connected across its diameter. The total resistance across its diameter AB will be
|
(a) |
(b) |
(c) 0.88 |
(d) 14π |