**Questions:**

1) Calculate the energy that a photon with a wavelength of 90nm has in a) joules b) eV?

2) In a photoelectric effect experiment, the stopping voltage has a magnitude of 4.2V. What is the maximum kinetic energy of the emitted photoelectrons?

3) Calculate the work function (in J) for copper if it has a threshold frequency of 1.135 × 10^{15} Hz:

4) Calculate the kinetic energy (in J and eV) of photoelectrons emitted from zinc when ultraviolet light with a frequency of 3.65 × 10^{15} Hz strikes its surface. Zinc has a work function of 6.90 × 10^{−19} J.