# 5F15.10 - Electrical Equivalent of Heat

Code Number:
5F15.10
Demo Title:
Electrical Equivalent of Heat
Condition:
Good
Principle:
Relationship between Thermal and Electrical Energy
Area of Study:
Electricity & Magnetism
Equipment:
Countdown Timer, Insulated Flask, 250 Watt Heater, AC Current Projection Meter, Ring Stand, Digital Thermometer, 2 Digital Meters (Amperage and Voltage), Cord for Multimeter, and Beaker with Water.
Procedure:

Set up as shown and by running the experiment for a set amount of time, measuring the voltage and current, and the temperature rise, you should be able to calculate the electrical equivalent of heat.

Measure 1 liter of water into the Dewar.  Place the covering which contains the heater and bead thermocouple onto the Dewar.  Set the countdown timer for 5 minutes.  This heater runs at about 3.5 amps and will heat the 1 liter of water approximately 30 degrees Celsius in 5 minutes.

If using the larger knife style heater with the above conditions you can expect the heater to run at about 2.5 amps and give a temperature rise of over 20 degrees Celsius in 5 minutes.

References:
• Thomas B. Greenslade Jr., "Nineteenth‐Century Measurements of the Mechanical Equivalent of Heat", TPT, Vol. 40, #4, Apr. 2002, p. 243.
• William Hooper, "No Cal", TPT, Vol. 31, #2, Feb. 1993, p. 68.
• Louie A. Galloway III and John F. Wilson Jr., "Measuring the Mechanical Equivalent of Heat—Electrically", TPT, Vol. 30, #8, Nov. 1992, p. 504.
• Brother T. G. Bullen, "Alternative Setup for Joule’s Law", TPT, Vol. 19, #5, May 1981, p. 280.
• Ronald F. Gleeson and Melvin Deak, "Joule's Law Experiment", TPT, Vol. 19, #2, Feb. 1981, p. 119.
• Bruce Jones, "A Stirring Experiment", TPT, Vol. 18, #9, Dec. 1980, p. 671, also A Potpourri of Physics Teaching Ideas - Odds and Ends, p. 310.
• Frank G. Karioris, "Tricks of the Trade: Inexpensive Immersion Heater", TPT, Vol. 12, #9, Dec. 1974, p. 573.
• Samuel C. Dickieson, "Relating Heat and Electrical Units with Immersion Heaters", TPT, Vol. 10, #5, May 1972, p. 268.
• T. E. Neil and P. D. Schulze, "Mechanical Equivalent of Heat: Electrical Method by Vaporization of Liquid Nitrogen", AJP, Vol. 54, #5, May 1986, p. 474.
• C. W. Tompson and H. W. White, "Latent Heat and Low-Temperature Heat Capacity Experiment for the General Physics Laboratory", AJP, Vol. 51, #4, Apr. 1983, p. 362.
• G. D. Freier and F. J. Anderson, "He-4", A Demonstration Handbook for Physics.
• G. D. Freier and F. J. Anderson, "Eh-3", A Demonstration Handbook for Physics.
• John L. Roeder, "Activity 6.Converting Electrical to Thermal Energy", Teaching About Energy, p. 83.
• David Kutliroff, "91. Heating Effect of an Electric Current", 101 Classroom Demonstrations and Experiment For Teaching Physics, p. 202.
• Robert Ehrlich, "L.10. Conversion of Electrical to Thermal Energy", Turning the World Inside Out and 174 Other Simple Physics Demonstrations, p. 152 - 153.

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