Forces of Nature

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Forces of Nature Lab

# Matter and Electrons

## Goal: To Measure emissivity from a light bulb and determine its blackbody properties. Be sure that you play with the two student exercises so that you understand Planck's distribution formula.

#### Materials

• A Crooke's radiometer (can be purchased for under $10 ) • A Leslie's cube (commercial ones can be purchased for$10-25, epending on suppliers and quality. ). You can also make a substitute Leslie's cube using a square metal container, and painting one side matte black, one side shiny black, one side white, and leaving one side as shiny metal. It should be large enough to hold a small 40W lightbulb and socket. Make a "floor" and lid of aluminum foil to retain the heat, with a hole in the floor for the socket cord. Make a hole in the lid so that you can suspend a thermometer above the light bulb.

#### Procedure

1. Follow the instructions at Web Physics 320 Lab.

#### Data Handling

1. Use the data handling instructions with the lab procedures.

## ALTERNATIVE LAB Goal: to observe changes in blackbody radiation at different temperatures.

Change the temperature of the blackbody and observe what happens to the emitted light.

#### Report

1. Describe your experiment in sufficient detail that another similarly equipped student could perform your tests.
2. Include your assessment that the light bulb acts/doesn't act as a blackbody over various temperature ranges.