MCQ
A very thin film in reflected white light appears:
- AViolet
- BWhite
- CBlack
- DRed
Explanation:
When the film is thin, t → 0, path diff. = $\frac{\lambda}{2}$. Therefore, in reflected light, the film appears black.
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The amount of heat produced in a resistor when a current is passed through it can be found using
|
(a) Faraday’s Law |
(b) Kirchhoff’s Law |
(c) Laplace’s Law |
(d) Joule’s Law |
The dispersive power is maximum for the material
|
(a) Flint glass |
(b) Crown glass |
(c) Mixture of both |
(d) None of the above |
$\frac{\text{l}_1+\text{l}_2}{2}$
$\sqrt{\text{l}_2\text{l}_2}$
$\frac{\text{l}_1\text{T}_2-\text{l}_2\text{T}_1}{\text{T}_2-\text{T}_1}$
$\frac{\text{l}_1\text{T}_2+\text{l}_2\text{T}_1}{\text{T}_2+\text{T}_1}$
The a-particle is the nucleus of an atom of
|
(a) Neon |
(b) Hydrogen |
(c) Helium |
(d) Deuterium |
Magnetic dipole moment is a
|
(a) Scalar quantity |
(b) Vector quantity |
(c) Constant quantity |
(d) None of these |
The photoelectric threshold wavelength of a certain metal is 3000Å. If the radiation of 2000Å is incident on the metal
|
(a) Electrons will be emitted |
(b) Positrons will be emitted |
|
(c) Protons will be emitted |
(d) Electrons will not be emitted |
We are able to obtain fairly large currents in a conductor because
|
(a) The electron drift speed is usually very large |
|
(b) The number density of free electrons is very high and this can compensate for the low values of the electron drift speed and the very small magnitude of the electron charge |
|
(c) The number density of free electrons as well as the electron drift speeds are very large and these compensate for the very small magnitude of the electron charge |
|
(d) The very small magnitude of the electron charge has to be divided by the still smaller product of the number density and drift speed to get the electric current |