Dark, rough, and dull surfaces absorb radiation better than light, smooth, and shiny surfaces.

Which one of the following statements is wrong? a. Physical adsorption of gas directly related to its critical temperature. b. Chemical adsorption decreases regularly as the temperature is increased. c. Adsorption is an exothermic process. d. A solid with a rough surface is a better adsorbent than the same solid with a smooth surface.

Which surfaces reflect light better-rough or smooth?

Give reasons for the following: Rough surface of a catalyst is more effective than smooth surface.

A parallel beam of monochromatic light of wavelength 500nm is incident normally on a perfectly absorbing surface. The power through any cross- section of the beam is 10 W. Find (a) the number of photons absorbed per second by the surface and (b) the force exerted by the light beam on the surface.

A parellel beam of monochromatic light of wavelength 500 nm is incident normally on a perfectly absorbing surface. The power through any cross section of the beam is 10 W. Find (a) the number of photons absorbed per second by the surface and (b) the force exerted by the light beam on the surface.

The sun having surface temperature Ts radiates like a black body. The rasius of sun is Rs and earth is at a distance R from the surface of sun. Earth absorbs radiations falling on its surface from sun only and is at constant temperature T. If radiations falling on earth's surface are alomost parallel and earth also radiates like a blackbody, then

The rate of radiation of energy from a hot object is maximum, if its surface is

Black surfaces are poor absorbers of heat radiations.

Black and dull surfaces are .............. of heat.

Lower surface of a plank is rough and lying at rest on a rough horizontal surface. Upper surface of the plank is smooth and has a smooth hemisphere placed over it through a light string as shown in the figure. After the string is burnt, trajectory of C.M , of the sphere is