Question

A metal surface is illuminated by photons of energy 5 eV and 2.5 eV respectively. The ratio of their wavelengths is ____________.

विकल्प

• 1 : 3

• 1 : 4

• 2 : 1

• 1 : 2

Answer 1

A metal surface is illuminated by photons of energy 5 eV and 2.5 eV respectively. The ratio of their wavelengths is 1 : 2.

Explanation:

`"E" = "hc"/lambda`

`"i.e."  "E" prop 1/lambda`

`therefore lambda_1/lambda_2 = "E"_2/"E"_1`

` = 2.5/5 = 1/2`

`therefore lambda_1 : lambda_2`

` = 1 : 2`