Suppose that the electric field part of an electromagnetic wave in vacuume is
`E=3.1N//C cos [(1.8rad//m)y+(5.4xx10^8rad//s)t]hati`
(a) What is the direction of motion?
(b) What is the wavelength `lambda`?
(c) What is the frequency v?
(d) What is the amplitude of the magnetic field part of the wave?
(e) Write an expression for the magnetic field part of the wave.

Explanation

A body at a particular temperature produces a continous spectrum of wavelengths. In case of a block boyd, the wavelength corresponding to maximum intensity of radiation is given according to planck's law. It can be given by the relation,
`gamma_(m)=(0.29)/(T)cmK`
Where,
`gamma_(m)=` maximum wavelength
T=temperature
Thus, the temperature for different wavelengths can be obtained as:
For `lambda_(m)=10^(-4)cm,T=(0.29)/(10^(-4))=2900^(@)K`
For `lambda_(m)=5xx10^(-5)cm,T=(0.29)/(5xx10^(-5))=5800^(@)K`
`T=(0.29)/(10^(-5))=290000^(@)K`
and so on.
The numbers obtained tell us that temperature ranges are required for obtaining radiations in different parts of an electromagnetic spectrum. As the wavelength decrease, the corresponding temperature increases.