Atoms — Physics STD 12 Science — Question

Critical mass is minimum mass necessary for:

An object is released from rest. The time it takes to fall through a distance h and the speed of the object as it falls through this distance are measured with a pendulum clock. The entire apparatus is taken on the moon and the experiment is repeated:

1. The measured times are same.
2. The measured speeds are same.
3. The actual times in the fall are equal.
4. The actual speeds are equal.

The magnitude of the electric field is given by the change in magnitude of potential per unit displacement _____ to the equipotential surface at the point.

A river is flowing from west to east at a speed of 5 metres per minute. A man on the south bank of the river, capable of swimming at 10 metres per minute in still water, wants to swim across the river in the shortest time. He should swim in a direction:

1. Due north.
2. 30° east of north.
3. 30° north of west.
4. 60° east of north.

The total power content of an AM wave is 900 W. For 100% modulation, the power transmitted by each side band is

(a) 50 W

(b) 100 W

(c) 150 W

(d) 200 W

What happens when a glass rod is rubbed with silk?

In the given figure, a current of constant magnitude is flowing in the wire AB. Direction of induced current flowing through the wire is:

When  ampere current is passed in a tangent galvanometer, there is a deflection of 30° in it. The deflection obtained when 3 amperes current is passed, is

(a) 30°

(b) 45°

(c) 60°

(d) 75°

Which of the following statements is correct in case of Thomson’s atomic model?