Electric Charges and Fields — Physics STD 12 Science — Question

In a diode valve, the state of saturation can be obtained easily by

(a) High plate voltage and high filament current

(b) Low filament current and high plate voltage

(c) Low plate voltage and high cathode temperature

(d) High filament current and high plate voltage

A caesium photocell, with a steady potential difference of 60V across, is illuminated by a bright point source of light 50 cm away. When the same light is placed 1m away the photoelectrons emitted from the cell

(a) Are one quarter as numerous

(b) Are half as numerous

(c) Each carry one quarter of their previous momentum

(d) Each carry one quarter of their previous energy

What is moving coil galvanometer used for?

The electric field inside a hollow conducting sphere:

After 1α and 2β emissions

(a) Mass number reduces by 3	(b) Mass number reduces by 4
(c) Mass number reduces by 6	(d) Atomic number remains unchanged

An AC voltmeter in an L - C - R circuit reads 30volt across resistance, 80 volt across inductance and 40 volt across capacitance. The value of applied voltage will be.

A prism ABC of angle 30° has its face AC silvered. A ray of light incident at an angle of 45° at the face AB retraces its path after refraction at face AB and reflection at face AC. The refractive index of the material of the prism is

(a) 1.5

(b)

(c)

(d)

The output of a dynamo using a splitting commutator is

(a) dc	(b) ac
(c) Fluctuating dc	(d) Half-wave rectified voltage