Question

Find energy of each of the photons which
a. correspond to light of frequency `3xx10^(15) Hz`.
b. have wavelength of `0.50 Å`.

Answer 1

(i) Energy (E) of a photon is given by the expression,
E=hv
Where
h = Planck’s constant =`6.626 xx10^(-34) Js`
ν = frequency of light = `3xx 10^(15)Hz`
Substituting the values in the given expression of E
` E= (6.626xx 10^(-34))(3xx10^(15))`
`E = 1.989 xx 10^(-18)J`
(ii) Energy (E) of a photon having wavelength (λ) is given by the expression,
`E=(hc)/lambda`
h = Planck’s constant `= 6.626 xx 10^(-34)Js`
c = velocity of light in vacuum =` 3xx 10^(8) m//s`
Substituting the values in the given expression of E:
`E=((6.626 xx 10^(-34))(3xx10^(8)))/(0.50xx 10^(-10))=3.976xx10^(-15) J`
` E = 3.98 xx 10^(-15) J`