Q1: The rate of emission of radiation by a body does not depend upon the

ANS:D - shape and porosity of the body.

The rate of emission of radiation by a body is governed by its temperature and surface properties, but it does not depend on the wavelength of radiation. Therefore, the statement "The rate of emission of radiation by a body does not depend upon the wavelength of radiation" is incorrect. The correct option from the given choices is: The rate of emission of radiation by a body does not depend upon the wavelength of radiation. Explanation:

• According to Planck's law and Stefan-Boltzmann law, the rate of emission of thermal radiation by a body is directly proportional to the fourth power of its absolute temperature (surface temperature of the body). This means that as the temperature of the body increases, the rate of radiation emission also increases.
• The nature of the surface affects the emissivity of the body, which is a measure of how efficiently the body emits thermal radiation compared to an ideal blackbody. Different surfaces have different emissivities, affecting the rate of radiation emission.
• The shape and porosity of the body may affect its ability to absorb and emit radiation but to a lesser extent compared to temperature and surface properties. However, they are still factors that influence the rate of radiation emission. For instance, a body with a complex shape or porous surface may have different absorption and emission characteristics compared to a smooth, solid surface.