The threshold wavelength for a certain metal is 2000 Å. The work function of the is

Options

A. 6.2J
B. 6.2eV
C. 6.2MeV
D. 6.2keV

Answer

B

Explanation

Threshold wavelength ,`lamda=2000A^(o)=2xx10^(-7)m`
The expression for work function is given as ,
`w=(hc)/(lamda_(o)`
`impliesw=((6.6xx10^(-34))xx(3xx10^(8)))/(2xx10^(-7)`
`w=9.9xx10^(-19)J`
Therefore
`impliesw=(9.9xx10^(-19))/(1.6xx10^(-19))eV`
`therefore=6.2eV`