About `5%` of the power of a `100 W` light bulb is converted to visible radiation. What is the average intensity of visible radiation
(a) at a distance of `1 m` from the bulb?
(b) at a distance of `10 m` ?
Assume that the radiation is esmitted isotropically and neglect reflection.

Explanation

(a) Radio waves: it belongs to the short wvelength end of the electromagnetic spectrum.
(b) Radio waves: it belongs to the short wavelength end.
(c) Temperature, T=`2.7^(@)K`
`lambda_(m)` is given by planck's law as:
`gamma_(m)=(0.29)/(2.7)=0.11cm`
this wavelength corresponds to microwves.
(d) This is the yellow light of the visible spectrum.
(e) Transition energy is given y the relation,
E=hv
where,
h=planck's constnat =`6.6xx10^(-34)Js`
v=Frequency of radiation
Energy, `E=14.4KeV`
`therefore V=(E)/(h)`
`=(14.4xx10(3)xx1.6xx10^(-19))/(6.6xx10^(-34))`
`=3.4xx10^(18)Hz`.
This corresponds to X=rays.