Question

Wavelength of a photon is 4000 A. It's energy will be..

Answer 1

Energy (E) of a photon = hc/λ

Where,λ = wavelength of light = 4000 pm = 4000 ×10–12 m = 4x 10-9 m

c = velocity of light in vacuum = 3 × 108 m/s

h = Planck’s constant = 6.626 × 10–34 Js

thefore the energy of photon (E)

= 6.626 × 10–34 Js X 3 × 108 m/s / 4x 10-9 m = 4.965 x 10-16 J

Now 4.965 x 10-16 J is the energy of = 1 photon

Therefore 1 J will be the energy of = 1/4.965 x 10-16 J = 2.014 x 1015photons

Answer 2

Answer:

4.97 × 10^-19 \ "Joule"

Explanation:

E = (hc)/λ

E = (hc)/λ = (6.626 × 10^-34\ "J s" × 3 × 10^8\ "m/s")/(4000 × 10^-10\ "m")

E = 4.97 × 10^-19 \ "Joule"

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