Code Number: 5K10.65
Demo Title: Earth Inductor - Jumping Rope
Condition: Excellent
Principle: Faraday's Law
Area of Study: Electricity and Magnetism
Equipment:
50 ft extension cord with banana plug ends, Galvanometer, Oscilloscope.
Procedure:
Attach the loop at one end of the extension cord to the hook on the wall in the lecture rooms. Stand in an east-west direction and spin one leg of the cord like a jump rope. In our conditions we use the galvanometer to show about a 3 mv AC voltage.
Although the oscilloscope is more sensitive and should give a nice sine wave when doing this experiment, the cord acting as an antennae, picks up too much electromagnetic radiation from the machine room located below the lecture rooms.
References:
- Jarier Wannous, Peter Horvath, "Precise Measurements Using a Smartphone's Magnetometer - Measuring Magnetic Fields and Permeability", TPT, Vol. 61, #1, Jan. 2023, p. 36.
- Roland Berger and Markus Schmitt, "Estimating the Earth's Magnetic Field Strength with an Extension Cord", TPT, Vol. 41, # 5, May 2003, p. 295.
- Stanislaw Bednarek, "Showing Forces in the Terrestrial Magnetic Field", TPT, Vol. 37, # 6, Sept. 1999, p. 383.
- Daniel L. Timmons, "Finding Magnetic North the Hard Way", TPT, Vol. 26, # 5, p. 276, May 1988.
- Herbert H. Gottlieb, "Earth Inductor", TPT, Vol. 5, # 2, Feb. 1967, p. 86.
- B- 210: "Jump Rope", DICK and RAE Physics Demo Notebook.
- Borislaw Bilash II, David Maiullo, "Tapping into the Earth's Magnetic Field", A Demo a Day: A Year of Physics Demonstrations, p. 306.
- Jearl Walker, "5.47, Solar Eruptions and Power Outages", The Flying Circus of Physics Ed. 2, p. 239.