PhysicsLAB AP Free Response Question
2000 B5

A sodium photoelectric surface with work function 2.3 eV is illuminated by electromagnetic radiation and emits electrons. The electrons travel toward a negatively charged cathode and complete the circuit shown above. The potential difference supplied by the power supply is increased, and when it reaches 4.5 V, no electrons reach the cathode.
(a) For the electrons emitted from the sodium surface, calculate the following.
 i. The maximum kinetic energy

 ii. The speed at this maximum kinetic energy

 (b) Calculate the wavelength of the radiation that is incident on the sodium surface.

 (c) Calculate the minimum frequency of light that will cause photoemission from this sodium surface.

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