What is the kinetic energy and speed of an electron ejected from a sodium surface whose work function is W = 2.28 eV when illuminated by light of wavelength a) 410 nm and b) 550 nm.

a) 1.25×10^-19J

b) 0J

Explanation:

We must first obtain the energy of the photons using their respective wavelengths given as shown in the solution attached. Then we convert the work function of the metal from electron volts to joules as shown. Then we apply Einstein's photoelectric equation as shown. This gives us the kinetic energy of the emitted photoelectron in each case. In the second wavelength does not have sufficient energy to impart kinetic energy to the emitted photo electrons.

another example of kinetic energy would be,

kinetic energy   >     moving energy

answer   >   letter choice (c),   a hammer falling off a table.

hope that !                                         : )