4D10.20 Brownian Motion Simulation

A large disk is placed in with small ball bearings in a shaker frame on an overhead projector to simulate what happens during Brownian motion.

Setup Requirements: Minimal. Need overhead projector and extension cord for simulator.

Equations: None

Safety Issues: Bare terminals on AC Adapter

Note:The belt that connected the motor to the moving frame broke and was replaced by a rubber band. If the frame does not vibrate, remove cover from motor and see if rubber band needs replacing.

4D20.10 Crookes Radiometer

Discuss different theories about how it works: photon momentum, hot surface/cold surface, edge effect and how one decides which is correct. Spins opposite to direction it would go due to photon momentum.

Setup Requirements: Minimal. Use large flashlight and hot air blower to show rotates in same direction.

Equations: None

Safety Issues: None

4D20.11 Crookes Radiometer & Emission

The idea that dark surfaces are better emitters than light surfaces can also be demonstrated using the radiometer. Use the hot air blower to heat it until it is spinning rapidly. Let it cool off. It will come to a stop and slowly rotate in the reverse direction.

Setup Requirements: Minimal. Need hot air blower

Equations: None

Safety Issues: Hot air blower