Ray Optics and Optical Instruments — Physics STD 12 Science — Question

In an elastic collision:

1. The initial kinetic energy is equal to the final kinetic energy.
2. The final kinetic energy is less than the initial kinetic energy.
3. The kinetic energy remains constant.
4. The kinetic energy first increases then decreases.

The time taken by sunlight to cross a 5 mm thick glass plate (μ = 3/2) is

(a) 0.25

(b) 0.167

(c) 2.5

(d) 1.0

A parallel beam of monochromatic light of wavelength 5000 Å is incident normally on a single narrow slit of width 0.001 mm. The light is focused by a convex lens on a screen placed on the focal plane. The first minimum will be formed for the angle of diffraction equal to

(a) 0o

(b) 15o

(c) 30o

(d) 60o

Two ions have equal masses but one is singly-ionised and the other is doubly-ionised. They are projected from the same place in a uniform magnetic field with the same velocity perpendicular to the field.

A parallel-plate capacitor has plates of unequal area. The larger plate is connected to the positive terminal of the battery and the smaller plate to its negative terminal. Let Q₊ and Q_- be the charges appearing on the positive and negative plates respectively:

1. Q₊ > Q_-
2. Q₊ = Q_-
3. Q₊ < Q_-
4. The information is not sufficient to decide the relation between Q₊ and Q_-.

A plane electromagnetic wave with a single frequency moves in vacuum in the positive x direction. Its amplitude is uniform over the yz plane. the amplitude of its magnetic field. 

A positively charged particle projected towards east is deflected towards north by a magnetic field. The field may be:

1. Towards west.
2. Towards south.
3. Upward.
4. Downward.

A heater of 220 V heats a volume of water in 5 minute time. A heater of 110 V heats the same volume of water in

(a) 5 minutes

(b) 8 minutes

(c) 10 minutes

(d) 20 minutes

Consider the two following statements A and B and identify the correct choice given in the answers;

(A) In photovlotaic cells the photoelectric current produced is not proportional to the, intensity of incident light.

(B) In gas filled photoemissive cells, the velocity of photoelectrons depends on the wavelength of the incident radiation.

(a) Both A and B are true	(b) Both A and B are false
(c) A is true but B is false	(d) A is false B is true

1 emu = __________ C