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

To get maximum current in a resistance of 3 ohms, one can use n rows of m cells (connected in series) connected in parallel. If the total number of cells is 24 and the internal resistance of a cell is 0.5 ohms then:

The work function of a photoelectric material is 3.3 eV. The threshold frequency will be equal to

(a) 8

(b) 8

(c) 8

(d) 8

What is the C.G.S. unit of charge?

Two free parallel wires carrying currents in opposite direction

(a) Attract each other

(b) Repel each other

(c) Neither attract nor repel

(d) Get rotated to be perpendicular to each other

A particle moves with a constant velocity parallel to the X-axis. Its angular momentum with respect to the origin:

1. Is zero.
2. Remains constant.
3. Goes on Increasing.
4. Goes on decreasing.

On increasing the distance between the light source and the photoelectric cell, the value of stopping potential changes :

A potential barrier of 0.50 V exists across a P-N junction. If the depletion region is  5.0  m wide, the intensity of the electric field in this region is

(a) 1.0

(b) 1.0

(c) 2.0

(d) 2.0

The electric intensity due to a dipole of length 10 cm and having a charge of 500μC, at a point on the axis at a distance 20 cm from one of the charges in air, is

(a) 6.25  N/C

(b) 9.28   N/C

(c) 13.1  N/C

(d)   N/C

A star emitting light of wavelength 5896 Å is moving away from the earth with a speed of 3600 km /sec. The wavelength of light observed on earth will (c = 3  is the speed of light)

(a) Decrease by 5825.25 Å	(b) Increase by 5966.75 Å
(c) Decrease by 70.75 Å	(d) Increase by 70.75 Å

A helium nucleus makes a full rotation in a circle of radius 0.8 metre in two seconds. The value of the magnetic field B at the centre of the circle will be

(a)

(b)

(c) 2

(d)