In a photoelectric effect experiment , the maximum kinetic energy of the ejected photoelectrons is measured for various wavelength of the incident light. Figure shows a graph of this maximum kinetic energy `K_(max)` as a function of the wavelength `lamda` of the light falling on the surface of the metal. Which of the following statement/i is/ are correct?

Options

A. Threshold frequency for the metal is `1.2xx10^(15)m`
B. Work function of the metal is 4.968 eV
C. Maximum kinetic energy of photoelectrons corresponding to light of wavelength 100 nm is nearly 7.4 eV
D. Photoelectric effect takes place with red light

Answer

A, B, C

Explanation

Cut off wavelength `lamda_0=250nm`
Threshold frequncy,
`v_0=(c)/(lamda_0)=(3xx10^(8))/(250xx10^(-9))Hz=1.2xx10^(15)Hz`
Work function of the metal,
`W=(hc)/(lamda_0)=(1242eVnm)/(250)=4.068eV`
`(hc)/(lamda)=(hc)/(lamda_0)+K_(max)`
`K_(max)=(1242eVnm)/(100nm)-4.968eV`
`=7.432eVapprox7.4eV`
Photoelectric effect takes placeonly for light of wavelength less than 250 nm, whereas `lamda_(red)approx700nm`.