7-An object at 27°C has its temperature increased to 37°C. Thepower then radiated by this object increases by how manypercent?a.3.3b.14c.37d.253ANS: B

A sphere of radius R has an absolute temperature T and it radiates power P. A second sphere has a radius 2R. The spheres can be assumed to be black-body radiators. Determine: a. the power radiated by the second sphere, when its absolute temperature is T b. the absolute temperature of the second sphere, when it radiates power P

The original temperature of a black body is 727∘C. Calculate temperature at which total radiant energy from this black body becomes double:

Which of the following does NOT occur when the temperature of a red-hot object increases?The amount of electromagnetic radiation which it emits increases at all wavelengthsIt emits more visible lightThe potential energy of the particles which make up the object decreasesThe shortest wavelength of the radiation which it emits decreases2The radiation produced by an infrared laser has a wavelength of 1054 nm.  Convert this wavelength to metres.1.054 × 10-9 m1.054 × 10-3 m1.054 × 10-12 m1.054 × 10-6 m3What happens to an object when it emits energy faster than it absorbs energy?Its temperature decreasesIts temperature remains constantIts temperature increasesIt is impossible to say what happens to the temperature of the object without knowing the specific heat capacity of the material from which it is made4Which of the following statements is incorrect?The intensity of the radiation which we receive from the Sun can be measured in joules per square metreThe intensity of the radiation which we receive from the Sun can be measured in watts per square metreThe intensity of the radiation which we receive from the Sun can be measured in joules per second per square metreThe intensity of the radiation which we receive from the Sun is higher at the Equator than it is at the poles5Which of the following statements is incorrect?Some of the radiation from the Sun which reaches the Earth is reflected by clouds and atmospheric gasesAll of the infrared radiation from the Sun which reaches the surface of the Earth is absorbedIf the overall rate at which energy from the Sun is absorbed by the Earth is greater than the overall rate at which energy is emitted into space, the temperature of the Earth will increaseIf the overall rate at which energy from the Sun is absorbed by the Earth is less than the overall rate at which energy is emitted into space, the temperature of the Earth will decrease

A metal rod at a temperature of 150oC, radiates energy at a rate of 20 W. If its temperature is increased to 300 o C, then itwill radiate at the rate of about

Two spheres P and Q of same colour having radii 8 cm and 2 cm are maintained at temperatures 127°𝐶  and 527°𝐶  respectively. The ratio of energy radiated by P and Q is