Unit V - Quantum Physics

As the wavelength of the radiation decreases, the intensity of the black body radiations

• Increases

• Decreases

• First increases then decrease

• First decreases then increase

The radiations emitted by hot bodies are called as

• X-rays

• Black-body radiation

• Gamma radiations

• Visible light

An iron rod is heated. The colors at different temperatures are noted. Which of the following colors shows that the iron rod is at the lowest temperature?

• Red

• Orange

• White

• Blue

A black body is defined as a perfect absorber of radiations. It may or may not be a perfect emitter of radiations.

• True

• False

From the figure, what’s the relation between T1, T2, and T3?

• T1 > T2 > T3

• T3 > T2 > T2

• T3 > T1 > T2

• T2 > T1 > T3

Electromagnetic wave theory of light could not explain Black Body radiations.

• True

• False

The energy emitted by a black surface should not vary in accordance with

• Wavelength

• Temperature

• Surface characteristics

• Time

The law governing the distribution of radiant energy over wavelength for a black body at fixed temperature is referred to as

• Kirchhoff’s law

• Planck’s law

• Wein’s formula

• Lambert’s law

The Planck’s constant h has the dimensions equal to

• M L 2 T -1

• M L T -1

• M L T -2

• M L T

The energy distribution is not uniform for any given temperature in a perfect black body.

• True

• False