Explanation:
As the work-function of the metal is
$\frac{\text{hc}}{\lambda_0}$, its threshold wavelength is $\lambda_0.$For photoelectric effect, the wavelength of the incident light should be less than or equal to the threshold wavelength of the metal on which light is incident.
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Critical angle for light going from medium (i) to (ii) is q. The speed of light in medium (i) is v then speed in medium (ii) is
|
(a) v(1- cosθ) |
(b) v/sinθ |
(c) v/cosθ |
(d) v(1- sinθ) |
The minimum deviation produced by a hollow prism filled with a certain liquid is found to be 30°. The light ray is also found to be refracted at angle of 30°. The refractive index of the liquid is
|
(a) |
(b) |
(c) |
(d) |
There are three voltmeters of the same range but of resistances 1000Ω, 8000 Ω and 4000 Ω respectively. The best voltmeter among these is the one whose resistance is
|
(a) 10000 W |
(b) 8000 W |
(c) 4000 W |
(d) All are equally good |
In a sample of radioactive material, what percentage of the initial number of active nuclei will decay during one mean life
|
(a) 69.3% |
(b) 63% |
(c) 50% |
(d) 37% |
A nucleus of an element 
emits an a-particle first, a b-particle next and then a gamma photon. The final nucleus formed has an atomic number
|
(a) 200 |
(b) 199 |
(c) 83 |
(d) 198 |
