Question

Suppose he work function for a metal used in the cathode of a photoelectric cell is 2.40x10-19 Joules. Calculate the value of the longest wavelength for light that has just sufficient energy to cause the emission of photoelectrons from the surface of this metal. What is the color of this light?

Answer 1

8.28.25nm

Step-by-step explanation:

E = 2.40 * 10 ^-19 J

h = 6.626 * 10^-34 J.S

C = 3.0 * 10^8 m/s

Energy - wavelength relationship is

E = hc / λ

λ = hc / E

λ = (6.626 * 10⁻³⁴ * 3.0*10⁸) / 2.40*10⁻¹⁹

λ = 8.28 * 10⁻⁷m

λ = 828.25nm

the wavelength is 828.25nm