Electromagnetic Waves — Physics STD 12 Science — Question

The electric field intensity at a point in vacuum is equal to:

A 20 cm length of a certain solution causes right-handed rotation of 38°. A 30cm length of another solution causes left-handed rotation of 24°. The optical rotation caused by 30cm length of a mixture of the above solutions in the volume ratio 1 : 2 is

(a) Left handed rotation of 14°	(b) Right handed rotation of 14°
(c) Left handed rotation of 3°	(d) Right handed rotation of 3°

Water is flowing through a long horizontal tube. Let P_A and P_B be the pressures at two points A and B of the tube.

1. P_A must be equal to P_B.
2. P_A must be greater than P_B.
3. P_A must be smaller than P_B.
4. P_A = P_B only if the cross- sectional area at A and B are equal.

The impact of an image on the retina remains for

(a) 0.1 sec

(b)  0.5 sec

(c) 10 sec

(d)  15 sec

Optoelectronic devices work on:

In a Young's double slit experiment, the slits are 2 mm apart and are illuminated with a mixture of two wavelength   and λ = 900 nm. The minimum distance from the common central bright fringe on a screen 2m  from the slits where a bright fringe from one interference pattern coincides with a bright fringe from the other is

(a) 1.5 mm

(b) 3 mm

(c) 4.5 mm

(d) 6 mm

A proton enters in a straight line in a uniform magnetic field along the field direction. How will its path and velocity change?

Which radiation in sunlight, causes heating effect

(a) Ultraviolet

(b) Infrared

(c) Visible light

(d) All of these

Which of the following are not electromagnetic waves

(a) Cosmic rays

(b) Gamma rays

(c) b-rays

(d) X-rays

Which of the following quantities do not change when a resistor connected to a battery is heated due to the current?

1. Drift speed.
2. Resistivity.
3. Resistance.
4. Number of free electrons.