Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

Light from a hydrogen discharge tube is incident on the cathode of a photoelectric cell the work function of the cathode surface is 4.2 eV. In order to reduce the photo-current to zero the voltage of the anode relative to the cathode must be made

(a) – 4.2 V

(b) – 9.4 V

(c) – 17.8 V

(d) +9.4 V

In an electric circuit containing a battery, the charge (assumed positive) inside the battery:

Order of magnitude of density of uranium nucleus is (

(a)

(b)

(c)

(d)

Electric flux per unit solid angle is defined as:

The band gap between the valence band and conduction band is the measure of ______?

If the wavelength of light in an experiment on photoelectric effect is doubled:

1. Photoelectric emission will not take place.
2. Photoelectric emission may or may not take place.
3. The stopping potential will increase.
4. The stopping potential will decrease.

In the given circuit, the voltmeter records 5 volts. The resistance of the voltmeter in ohms is

(a) 200

(b) 100

(c) 10

(d) 50

Bohrs atomic model assumes:

The critical angle between an equilateral prism and air is 45°. If the incident ray is perpendicular to the refracting surface, then

(a) After deviation it will emerge from the second refracting surface

(b) It is totally reflected on the second surface and emerges out perpendicularly from third surface in air

(c) It is totally reflected from the second and third refracting surfaces and finally emerges out from the first surface

(d) It is totally reflected from all the three sides of prism and never emerges out