Determining Planck’s Constant Through

The Photoelectric Effect

Presenter: Janelle Griswold

Presenter Status: Undergraduate student

Academic Year: 20-21

Semester: Spring

Faculty Mentor: Hongtao Shi

Department: Physics & Astronomy

Screenshot URL: https://drive.google.com/uc?id=1C72txwMQsfSmgl6KRPOZRBnrHgJ4GAQp

Abstract:
Planck’s constant, h, is a very important constant in the history of modern physics. It tells us how much quantized energy of a photon would increase when the frequency of its electromagnetic wave increases.

This is a teaching experiment to demonstrate the determination of such fundamental constant for future physic demos and labs by using the photoelectric effect. According to Einstein’s theory of photoelectric effect, the energy of a photon equals hf, where h is the Planck constant and f is the frequency of the electromagnetic radiation. Such energy can be used to overcome the binding energy of the electron, also known as the work function. The kinetic energy of the emitted electrons can be measured by tuning the opposing electric potential to a critical value, known as the stopping voltage Vs, after which no more electrons can be emitted from the surface of the material.