Dual Nature of Radiation and Matter — Physics STD 12 Science — Question

What will be the angle of diffracting for the first minimum due to Fraunhoffer diffraction with sources of light of wave length 550 nm and slit of width 0.55 mm

(a) 0.001 rad

(b) 0.01 rad

(c) 1 rad

(d) 0.1 rad

In a situation the contact force by a rough horizontal surface on a body placed on it has constant magnitude. If the angle between this force and the vertical is decreased, the frictional force between the surface and the body will:

1. Increase.
2. Decrease.
3. Remain the saint.
4. May increase or decrease.

The permanent magnetic moment of the atoms of a material is zero. The material:

A piece of cloud having area 25   and electric potential of  volts. If the height of cloud is 0.75 km, then energy of electric field between earth and cloud will be

(a) 250 J

(b) 750 J

(c) 1225 J

(d) 1475 J

Which of the following is false for electric lines of force ?

Choose the correct option:

A very long straight wire carries a current I. At the instant when a charge +Q  at point P  has velocity , as shown, the force on the charge is

(a) Opposite to OX

(b) Along OX

(c) Opposite to OY

(d) Along OY

By increasing the temperature, the specific resistance of a conductor and a semiconductor:

For a particle executing simple harmonic motion, the acceleration is proportional to:

1. Displacement from the mean position.
2. Distance from the mean position.
3. Distance travelled since t = 0.
4. Speed.

For the diode, the characteristic curves are given at different temperature. The relation between the temperatures is

(a)

(b)

(c)

(d) None of the above