Radiation: Processes and Properties

This quiz contains multiple-choice problems on various concepts, including transmissivity, absorptivity, reflectivity, black body concepts, Planck’s law, Stefan-Boltzman’s law, Wein’s law, Kirchhoff’s law, radiation intensity and solar radiations.

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Transmissivity is defined as

Fraction of total energy transmitted by the body Fraction of total energy reflected by the body Fraction of total energy absorbed by the body Fraction of total energy absorbed and radiated by the body

With respect to incident radiation, transmissivity varies with

Time Temperature Surface area Wavelength

Thin glass plate is an example of

Transparent body Opaque body Black body White body

The value of transmissivity may vary from

0-1

1-2

3-4

4-5

Transmissivity can be defined as the ratio of transmitted radiation to the incident energy flow. True or false?

True

False

What is the wavelength band of gamma rays?

1*10^(-7) to 4*10^(-4) μm

2*10^(-7) to 2.4*10^(-4) μm

3*10^(-7) to 3.4*10^(-4) μm

4*10^(-7) to 1.4*10^(-4) μm

Radiant energy with an intensity of 800 W/m^2 strikes a flat plate normally. The absorptivity is thrice the reflectivity and twice the transmissivity. Determine the rate of transmission.

155.47 W/m^2

145.47 W/m^2

135.47 W/m^2

125.47 W/m^2

A body through which all the incident radiations passes is called

Opaque body

Black body

Transparent body

White body

A polished metal pipe with 5 cm outer diameter and 370 K outer surface temperature is exposed to ambient conditions at 295 K. The surface’s emissivity is 0.2, and the convection coefficient of heat transfer is 11.35 W/m^2 degree. Calculate the overall heat transfer coefficient by the combined mode of convection and radiation.

11.04 W/m^2 degree

12.04 W/m^2 degree

13.04 W/m^2 degree

14.04 W/m^2 degree

Which of the following statements is true for an opaque body?

Transmissivity is zero

Reflectivity is zero

Absorptivity is zero

Reflectivity is unity

Radiant energy with an 800 W/m^2 intensity strikes a flat plate normally. The absorptivity is thrice the reflectivity and twice the transmissivity. Determine the rate of reflection.

518.20 W/m^2

418.20 W/m^2

318.20 W/m^2

218.20 W/m^2

Of 350 W/m^2 radiant energy incident upon a surface, 250 W/m^2 is absorbed, 60 W/m^2 is reflected, and the remainder is transmitted through the surface. What is the value of the surface material’s absorptivity?

0.113

0.114

0.115

0.116

Which of the following statements is true regarding gases?

Reflectivity is unity

Absorptivity is zero

Reflectivity is zero

Transmissivity is zero

When a surface absorbs a certain fixed percentage of striking radiation, the surface is called

Grey body

Black body