Field Lines of a Wire

The two ends of a long wire are connected to a 12 V car battery through a high capacity knife switch. The magnetic field lines near the wire are demonstrated with the aid of iron fillings sprinkled over a cardboard surface. When the switch is closed for a short time the iron fillings are caused to line up in circles around the wire. (It is important to immediately reopen the switch to prevent overheating.)
Equipment:
Car battery (12 V)
Straight wire
Piece of white cardboard
Connecting wires
Knife switch
Iron fillings
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This video is part of the project "Videos of Physics Demonstrations", which is created by Dr. Galli and Dr. Amiri of Physics Department, Weber State University. To access the full library of the videos, please visit this link: www.weber.edu/...
Links to University and Department:
Weber State University Homepage: www.weber.edu/
WSU Physics Department: www.weber.edu/...