Communication System — Physics STD 12 Science — Question

If Young's double slit experiment is performed in water:

1. The fringe width will decrease.
2. The fringe width will increase.
3. The fringe width will remain unchanged.
4. There will be no fringe.

Ampere’s circuital law is equivalent to:

What is the atomic mass (u) of sodium?

The state of photo-electrons emerging from the metal surface can be :

The output of a dynamo using a splitting commutator is

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

The length of a given cylindrical wire is increased by 100 %.  Due to the consequent decrease in diameter the change in the resistance of the wire will be

(a) 300 %

(b) 200 %

(c) 100 %

(d) 50 %

Two ions having masses in the ratio 1 : 1 and charges 1 : 2 are projected into uniform magnetic field perpendicular to the field with speeds in the ratio 2 : 3. The ratio of the radii of circular paths along which the two particles move is

(a) 4 : 3

(b) 2 : 3

(c) 3 : 1

(d) 1 : 4

The electric field lines are far apart where electric field is:

Assertion   :   The quantity L/R possesses dimensions of time.

Reason       : To reduce the rate of increases of current through a solenoid should increase the time constant (L/R).

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c) If assertion is true but reason is false.

(d) If the assertion and reason both are false.

A lens is placed between a source of light and a wall. It forms images of area  and  on the wall for its two different positions. The area of the source or light is

(a)

(b)

(c)

(d)