Atoms — Physics STD 12 Science — Question

A ray of light is incident at 50° on the middle of one of the two mirrors arranged at an angle of 60° between them. The ray then touches the second mirror, get reflected back to the first mirror, making an angle of incidence of

(a) 50°

(b) 60°

(c) 70°

(d) 80°

A ball of mass 1 g and charge   moves from a point A. where potential is 600 volt to the point B where potential is zero. Velocity of the ball at the point B is 20 cm/s. The velocity of the ball at the point A will be

(a) 22.8 cm/s

(b) 228 cm/s

(c) 16.8 m/s

(d) 168 m/s

Which of the following physical quantities is a vector ?

If the amplitude ratio of two sources producing interference is 3 : 5, the ratio of intensities at maxima and minima is

(a) 25 : 16

(b) 5 : 3

(c) 16 : 1

(d) 25 : 9

The neutron was discovered by

(a) Marie Curie

(b) Pierre Curie

(c) James Chadwick

(d) Rutherford

If the relative permeability of a substance is 0.999 then its nature is :

A dip circle is taken to geomagnetic equator. The needle is allowed to move in a vertical plane perpendicular to the magnetic meridian. The needle will stay:

1. In horizontal direction only.
2. In vertical direction only.
3. In any direction except vertical and horizontal.
4. In the direction it is released.

In summer, a mild wind is often found on the shore of a calm river. This is caused due to,

1. Difference in thermal conductivity of water and soil.
2. Convection currents.
3. Conduction between air and the soil.
4. Radiation from the soil.

A circular coil and a bar magnet moves with the same velocity. Then