Question

When a light of wavelength 4000 Å falls on a photoelectric emitter, photoelectrons are liberated. For another emitter, light of wavelength 6000 Å is sufficient for photo emission. The work functions of the two emitters are in the ratio of ____________.

Options

• 3 : 2

• 3 : 5

• 5 : 3

• 2 : 3

Answer 1

When a light of wavelength 4000 Å falls on a photoelectric emitter, photoelectrons are liberated. For another emitter, light of wavelength 6000 Å is sufficient for photo emission. The work functions of the two emitters are in the ratio of 3 : 2.

Explanation:

`phi = ("hc")/lambda_0`

`"Case (i)"  lambda_1 = ("hc")/phi_1`

`"Case (ii)"  lambda_2 = ("hc")/phi_2`

Dividing equation (i) by (ii),

`therefore  lambda_1/lambda _2 = (phi_0)_2/(phi_0)_1 = (6000 xx10^-10)/(4000 xx 10^-10) = 3/2`