Additional Info

• ID Code: P2-01
• Purpose: Demonstrate the frequency dependence of the photoelectric effect and determine the value of Planck's constant.
• Description: This apparatus uses an intense broad-spectrum mercury lamp shining through filters of various frequencies to activate a photoelectric tube. A finely controlled DC power supply is used to create a stopping potential across the PE tube. By measuring the voltage required to stop electrons from being emitted by the photoelectric effect at different frequencies, we can work backwards to then calculate h/e.

  Allow the mercury lamp 5-10 minutes to warm up, then remove the covers from the lamp and the PE tube. For each frequency filter, adjust the input stopping voltage from the tunable power supply until the current measured on the the current amplifier reaches 0.

  Plot the five frequencies (c/wavelength) vs the voltage, and the slope should be h/e. By assuming a standard value for e, h can be computed, or vice versa.

• Availability: Available
• References: REFERENCES: (PIRA 7A10.00)
• Loc codes: P2