Science (English Medium) Class 12 - CBSE Question Bank Solutions

Write two points of difference between an interference pattern and a diffraction pattern.

How can you differentiate whether a pattern is produced by a single slit or double slit?

Derive the expression for the angular position of (i) bright and (ii) dark fringes produced in a single slit diffraction.

In a diffraction pattern due to a single slit, how will the angular width of the central maximum change, if orange light is used in place of green light?

Justify your answer.

In a diffraction pattern due to a single slit, how will the angular width of the central maximum change, if the screen is moved closer to the slit?

Justify your answer.

In a diffraction pattern due to a single slit, how will the angular width of the central maximum change, if the slit width is decreased?

Justify your answer.

Draw the intensity distribution for the fringes produced in interference ?

Why are coherent sources necessary to produce a sustained interference pattern?

State the importance of coherent sources in the phenomenon of interference.

Can we conclude from the interference phenomenon whether light is a transverse wave or a longitudinal wave?

Why don't we have interference when two candles are placed close to each other and the intensity is seen on a distant screen? What happens if the candles are replaced by laser sources?

What is the luminous flux of a source emitting radio waves?

The luminous flux of a 1 W sodium vapour lamp is more than that of a 10 kW source of ultraviolet radiation. Comment.

Light is incident normally on a small plane surface. If the surface is rotated by an angle of 30° about the incident light, does the illuminance of the surface increase, decreases or remain same? Does your answer change if the light did not fall normally on the surface?

A bulb is hanging over a table. At which portion of the table is the illuminance maximum? If a plane mirror is placed above the bulb facing the table, will the illuminance on the table increase?

The sun is less bright at morning and evening as compared to at noon although its distance from the observer is almost the same Why?

Why is the luminous efficiency small for a filament bulb as compared to a mercury vapour lamp?

The yellow colour has a greater luminous efficiency as compared to the other colours. Can we increase the illuminating power of a white light source by putting a yellow plastic paper around this source?

The one parameter that determines the brightness of a light source sensed by an eye is ____________ .

Three light sources A, B and C emit equal amount of radiant energy per unit time. The wavelengths emitted by the three source are 450 nm, 555 nm and 700 nm respectively. The brightness sensed by an eye for the sources are X_A, X_B and X_C respectively. Then, ________ .