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In: English and Literature

Submitted By chaosley
Words 859
Pages 4
Photoelectric Effect

Objectives: • To be able to explain how the photoelectric effect experiment works and why a photon model of light is necessary to explain the results. • To study the effect of intensity of light on photoelectric experiment. • To estimate the Planck’s constant, h through the simulation. • To be determine how to calculate the wavelength of light, the work function of the metal, or the stopping potential, if given the other two.

Beginning with the plate made of sodium. Keep all the parameters constant except for the colour (wavelength) of the light and display all the graphs available.

1. Have the light source turned on at very low intensity and battery set to ZERO volts. Vary the wavelength of the light source (from Infra Red to Ultra Violet) until electrons just begin to be ejected from the sodium surface. State the wavelength and note the speed of the electrons. What is the corresponding frequency of the electromagnetic wave? Why is it called threshold frequency? Intensity is set at 1%. Wavelength = 370-395nm, energy = 1eV, speed of electrons = of different speed, some fast and some slow. The corresponding frequency will be 7.59 ( 1014 Hz – 8.11 ( 1014 Hz. It is called threshold frequency because it is the minimum frequency needed in order for the photoelectric to take place.

2. Repeat the instruction 1 above but allow the light to shine on the metal for a longer time before the wavelength is varied. Is your finding different as found in 1? Justify your finding. Yes, wavelength = 400nm (longer). The longer the light shines on the metal, the more photons to give energy to the electrons in the metal.

3. Repeat the instruction 1 above again but vary the intensity of light this time. Is your finding different as found in 1 and 2? Yes. The wavelength becomes longer (about 540 nm).…...

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