The stopping potential for the photo-electrons emitted from a metal surface of work-function 1.7 eV is 10.4 eV. Find the wavelength of the radiation used. Also identify the energy-levels in hydrogen atom which will emit this wavelength.

Options

A. The wavelength of light used is `1022 Å`
B. The wavelength of light used is `970.6 Å`
C. The light used is emitted by hydrogen gas sample which de-excites from `n = 3` to `n = 1`
D. The light used is emitted by hydrogen gas sample which de-excites from `n = 3` to `n = 1`

Answer

A, C

Explanation

`K_(max) = 10.4 eV , phi = 1.7 eV`
`E = 10.4 + 1.7 = 12.1 eV rArr n = 3 ` to `n = 1`
`12.1 = (1242.eVÅ)/(lambda)`