The work function for metals `A , B` and `C` are respectively `1.92 eV , 2.0 eV` and `5 eV`. According to Einstein's equation , the metals which will emit photoelectrons for a radiation of wavelength `4100 Å` are

Options

A. A only
B. A and B
C. Both (a) and (b)
D. Neither (a) nor (b)

Answer

B

Explanation

Work function for wavelength of 4100 Å is
`W=(hc)/(lamda)=(6.62xx10^(-34)xx3xx10^(8))/(4100xx10^(-10))`
`=4.8xx10^(-19)J`
`=(4.8xx10^(-19))/(1.6xx10^(-19)) eV=3eV`
Now, we have `W_(A)=1.92 eV,W_(B)=2.0eV,W_(C)=5eV`
Since, `W_(A) lt W`
and `W_(B) lt W` hence A and B will emit photoelectrons.