Demonstrations

Radiometer

Code Number :	4D20.10
Disclaimer:	Reprinted by permission of Dick Berg, University of Maryland, for use on this website. The demonstrations contained and referenced herein are listed for the purposes of cataloging and describing physics demonstrations which should be conducted only under the direction of a trained instructional support professional or physicist. These demonstrations are not presented for the purpose of being conducted by persons unconnected to this Facility and/or persons not consulting with or being supervised by the recognized instructional support professional or physicist and his/her staff. The University is responsible only for those demonstrations carried out using its own equipment using established safety and scheduling policies, and bears no responsibility for those choosing to use this source material for their own purposes. All demonstrations described and contained herein are public domain, and can also be found in reference materials in libraries, bookstores, and electronic sources. Further information regarding legal liability in use of demonstrations and labs will be found on the web site Injuries in School/College Laboratories in USA. The University of Iowa Disclaimers: University of Iowa Disclaimer All Rights Reserved..
Condition :	Excellent
Principle :	Energy Transfer, Heat Conduction
Area of Study :	Heat & Fluids
Equipment :	Radiometer, Flashlight, 100 or 1000 Watt light bulbs or IR heat lamp, Variac, IR absorbing filter.
Procedure :	The vanes can be made to turn by warming the bulb with your hands. A beam of light from a flashlight or a regular light bulb will also make it spin. The more the energy transfer the faster it will spin. The IR heat lamp will work the best of any of the sources here. Just lay it on its side on the table and point it at the radiometer. Turn the variac up to 20 on the dial and the radiometer will start to turn very fast even though the heat lamp does not get hot. One of the variations to do with the heat lamp and the radiometer is to place the IR absorbing filter between the two when the radiometer is spinning. The radiometer will slow down or even stop depending upon the quality of the filter. Use the IR heat lamp turned up to a sufficient voltage to heat the radiometer to a high temperature. Remove the heat lamp and watch the radiometer as it cools down. It should slow down, then stop, and then start turning in the opposite direction for a short while. This is indicative of the difference in heat emission between the two sides of the vanes.

References

William Crookes, "On Attraction and Repulsion Resulting from Radiation", Philosophical Transaction of the Royal Society of London, Vol. 164, (1874), 501- 527.

William Crookes, "On Repulsion Resulting from Radiation" Part II, Philosophical Transaction of the Royal Society of London, Vol. 165, (1875), 519- 547.

William Crookes, "On Repulsion Resulting from Radiation" Part III. & IV, Philosophical Transaction of the Royal Society of London, Vol. 166, (1876), 325- 376.

William Crookes, "On Repulsion Resulting from Radiation" Part V, Philosophical Transaction of the Royal Society of London, Vol. 169, (1878), 243- 318.

William Crookes, "On Repulsion Resulting from Radiation" Part VI, Philosophical Transaction of the Royal Society of London, Vol. 170, (1879), 87- 134.

Bruce Denardo, Timothy G. Simmons, "An Acoustic Radiometer", AJP, Vol. 72, # 6, June 2004, p. 843.

Edward V. Lee, "Detecting Infrared Radiation with a Photo-Transistor and an IR Filter," TPT, Vol. 42, # 2, Feb. 2004, p. 83.

"Holiday Gifts for the Physics Teacher Who has Everything", TPT, Vol. 12, # 9, Dec. 1974, p. 552.

Arthur E. Woodruff, "The Radiometer and How It Does Not Work", TPT, Vol. 6, # 7, Oct. 1968, p. 358.

Richard A. Bartels, "Do Darker Object Really Cool Faster?" AJP, 244, Vol. 58, No. 3, (March 1990).

Frank S. Crawford, "Letters to the Editor: Running Crooke's Radiometer Backwards," AJP, 490, Vol. 54, No. 6, (June 1986).

Frank S. Crawford, "Running Crooke's Radiometer Backwards," AJP, p. 1105, Vol. 53, No. 11, (November 1985).

S.L. Paveri-Fontana, "An Elementary Model for the Radiometer", AJP, Vol. 45, # 5, May 1977, p. 447.

Carl Kenty, "The Calorotor: A Simple Heat Engine with Which the Motion of Individual Molecules may be Demonstrated", AJP, Vol. 35, # 12, Dec. 1967, p. 1120.

Nathaniel E. Hager, Jr., "A Student Radiometer", AJP, Vol. 33, 1965, p. 92.

Hh- 6: Freier and Anderson, A Demonstration Handbook for Physics Demonstrations.

H-188: "Radiometer and Solar Cube," DICK and RAE Physics Demo Notebook.

H-164, 165, 166: Richard Manliffe Sutton, Demonstration Experiments in Physics.

1.8: Robert Ehrlich, "Getting the Physics Right," Why Toast Lands Jelly-Side Down.

"71. Crooke's Radiometer I," Christopher P. Jargodzki and Franklin Potter, Mad About Physics, p. 22, 173.

"72. Crooke's Radiometer II," Christopher P. Jargodzki and Franklin Potter, Mad About Physics, p. 23, 174.

H.J. Press, "Light Mill," Giant Book of Science Experiments, p. 220.

Richard Berg, "Reversing the Crooke's Radiometer Demonstration," PIRA News, Vol. 8, No. 2.

Robert Ehrlich, "Radiometer," Turning the World Inside Out, p. 117-118.

Mail Questions and Comments to: Dale Stille