When a yellow light of wavelength `6000Å` from a sodium lamp falls on a certain photocell, a negative potential of `0.30` volt is needed to stop all the electtons from reaching the collector. Then choose correct option (s)

Options

A. Work function of the given photocel is `25.5eV` approximately
B. Work function of the given photocell is `1.8eV` approximately
C. A negative potential of `0.6` Volt will be needed to stop all the electrons if light if of wavelength `lamda=4000Å` is used
D. A negative potential of `1.3` Volt will be needed to stop all the electrons if light of wavelength `lamda=4000Å` is used

Answer

B, D

Explanation

As we know that
`(hC)/(lamda)=phi+kimplies12400/(lamda)=phi+v_(s)`, where `phi` is in electron Volt and `lamda` is in `A`
When light of wavelenght `lamda=6000Å` is used
`12400/6000=phi+0.3impliesphi=1.77~~1.8eV` (approximately)
When light with wavelength `lamda=4000Å` is used
`12400/4000=phi+eV`
`implieseV=(3.1-1.8)e` volt `=1.3eV`
`impliesv=1.3` volt