Electrons are emitted with zero velocity from a metal surface when it is exposed to radiation of wavelength ` 6800` Å . Calculate threshold frequency `( v_0)` and work function `(W_0)` of the metal.

Explanation

Threshold wavelength of radian `(lambda_(0))=6800A=6800xx10^(-10)m`
Threshold frequency` (V_(0))` of the meta
`c/lambda=(3xx10^(8)ms^(-1))/(6.8xx10^(-7)m) =4.41xx10^(14)s^(-1)`
Thus, the threshold frequency `(v_(0))`of the metal is `4.41xx10^(14)s^(-1)`
Hence, work function `(W_(0))` of the metal = `hν_(0)`
` (6.626xx10^(-34)Js)(4.41xx10^(14 s^(-1)))`
`2.922xx10^(-19) J`