Question

What is the energy of a single photon of blue light with a wavelength of 488 nm (488 × 10-9 m)?

Answer 1

E = hf

c = speed of electromagnetic wave, c ≈ 3 * 10⁸ m/s,
Planck's constant h = 6.63 *10⁻³⁴ Js

h = Planck's constnat, Frquency, f = c/λ = (3*10⁸)/(488*10⁻⁹)

E = hf

E = hc/λ

E = (6.63 * 10⁻³⁴ * 3 * 10⁸) /(488 * 10⁻⁹)

Energy, E ≈ 4.0758 * 10⁻¹⁹ Joules.

Answer 2

Answer : The energy of a photon is,
`4.073* 10^(-19)J`

Explanation :

Formula used :

`E=(h* c)/(\lambda)`

where,

E = energy = ?

h = Planck's constant =
`6.626* 10^(-34)Js`

c = speed of light =
`3* 10^8m/s`

`\lambda` = wavelength =
`488* 10^(-9)m`

Now put all the given values in the above formula, we get the energy.

`E=((6.626* 10^(-34)Js)* (3* 10^8m/s))/(488* 10^(-9)m)`

`E=4.073* 10^(-19)J`

Therefore, the energy of a photon is,
`4.073* 10^(-19)J`