Answer:
The equation of photoelectric effect is given as,
hf = Kmax + work function
Kmax is the kinectic energy of the emitted electron, hf is photon energy transferred to a single electron in the material of the target.
From the equation above,
Work function = hf - Kmax.
hf = hc/wavelength
h = 6.63 x 10^-34J.S, c = 2.98 x 10^8m/s, wavelength = 300nm = 300 x 10^-9m, Kmax = 2.2eV = 2.2 x 1.6 x10^-19.
Work function = [( 6.63 x 10^-34 J.S * 2.28 x 10^8 m/s)/(300 x 10^-9)] - [2.2 * 1.6 x 10^-19]
work function = 3.07 x 10^-19V = 1.92eV
Maximum wavelength of light for photoelectric effect to occur in cesium
Wavelength = c/f. with f known, that wavelength can be calculated from the equation