Question

The terminology of different parts of the electromagnetic spectrumis given in the text. Use the formula E = hn (for energy of a quantumof radiation: photon) and obtain the photon energy in units of eV fordifferent parts of the electromagnetic spectrum. In what way arethe different scales of photon energies that you obtain related to thesources of electromagnetic radiation?

Answer 1

The energy of a photon is given as,

E=hv = hc λ

Where, h is the Planck's constant, c is the speed of light and λ is the wavelength.

By substituting the values of h and c in the above equation, we get

E= 6.626× 10 −34 ×3× 10 8 λ  J = 19.878× 10 −26 λ×( 1.6× 10 −19 )  eV = 12.424× 10 −7 λ  eV

The list of the photon energy as per the electromagnetic spectrum is given in table below:

Wavelength, λ( m )	Energy, E( eV )
10 3	1.242× 10 −9
1	1.242× 10 −3
10 −3	1.242× 10 −3
10 −6	1.242
10 −8	1.242× 10 2
10 −10	1.242× 10 4
10 −12	1.242× 10 6

The photon energy obtained for the different parts of electromagnetic spectrum shows the spacing of energy levels of the source.