According to Planck's quantum theory of light, every source of radiation emits photons (i.e., packets of energy ) which travel in all directions with the same speed (i.e., speed of light). Each photon is of energy `E=hv=hc//lambda`, where h is Planck's constant, v is the frequency and `lambda` is wavelength of radiation emitted. The photons emitted from different sources of radiation are different. Read the above passage and answer the following questions:
(i) on what factors does the number of photons emitted per second from a source of radiations depends?
(ii) Why are the high energy photons not vissible to eye?
(iii) Which basic values do you learn from this study?

Explanation

(i)The number of photons emitted per second from a source of radiation depends on its temperature, nature and area of radiating surface.
(ii) The ratina of our eye is senstive to visible light whose frequency range is `4xx10^(14)Hz` to `8xx10^(14)Hz`. High energy photons are of frequency much higher than `8xx10^(14)Hz`. They do not produce any sensation on our ratina. Hence, they can not be seen by our eyes.
(iii) We have learnt that every source emits radiations (i.e., photons). The different source emit radiation of different energies, which have different effects on the exposed bodies. The radiation of holy persons cultivate in us the good qualities and radiations of criminals develop bad qualities. Therefore, we must live in a company of good people for better and peaceful life.