012-04049J
h/e Apparatus and h/e Apparatus Accessory Kit
7
®
According to the photon theory of light, the maximum kinetic energy,
KE
max
, of photoelectrons
depends only on the frequency of the incident light, and is independent of the intensity. Thus
the higher the frequency of the light, the greater its energy.
In contrast, the classical wave model of light predicted that
KE
max
would depend on light inten-
sity. In other words, the brighter the light, the greater its energy.
This lab investigates both of these assertions. Part A selects two spectral lines from a mercury
light source and investigates the maximum energy of the photoelectrons as a function of the
intensity. Part B selects different spectral lines and investigates the maximum energy of the
photoelectrons as a function of the frequency of the light.
Setup
Set up the equipment as shown in the diagram below. Focus the light from the Mercury Vapor
Light Source onto the slot in the white reflective mask on the h/e Apparatus. Tilt the Light
Shield of the Apparatus out of the way to reveal the white photodiode mask inside the Appara-
tus. Slide the Lens/Grating assembly forward and back on its support rods until you achieve the
sharpest image of the aperture centered on the hole in the photodiode mask. Secure the
Lens/Grating by tightening the thumbscrew.
Align the system by rotating the h/e Apparatus on its support base so that the same color light
that falls on the opening of the light screen falls on the window in the photodiode mask, with no
overlap of color from other spectral lines. Return the Light Shield to its closed position.
Check the polarity of the leads from your digital voltmeter (DVM), and connect them to the
OUTPUT terminals of the same polarity on the h/e Apparatus.
Experiment 1: The Wave Model of light
vs. the Quantum Model
Experiment 1. Equipment Setup
Содержание h/e Apparatus
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