Question

The light produced by the electron in strontium has a wavelength of 608 nm. How much energy must be added to strontium to get it to produce this wavelength

Answer 1

According to Einstein the energy of photon is given by the equation,

E = hν = h . c/λ

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

Given, wavelength = 608 nm = 608 x 10⁻⁹ m  

Conversion factor: 1 nm = 10⁻⁹ m  

c = 3 x 10⁸ m/s

h = 6.626× 10⁻³⁴ J.s

Substituting the data into the equation we get,  

E = h . c/λ

E = 6.626× 10⁻³⁴ J.s x (3 x 10⁸ m/s) / 608 x 10⁻⁹ m  

E =  3.27 x 10⁻¹⁹J

3.27 x 10⁻¹⁹J  energy must be added to strontium to get it to produce 608 nm wavelength.