Faraday's Apparatus
This is Faraday's apparatus for demonstrating that a magnetic field can produce a current. A change in the field produced by the top coil induces an EMF and, hence, a current in the bottom coil. When the switch is opened and closed, the galvanometer registers currents in opposite directions. No current flows through the galvanometer when the switch remains closed or open.
Source
Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:
"OpenStax College, Induced Emf and Magnetic Flux. February 7, 2013."
http://cnx.org/content/m42390/latest/
OpenStax CNX
CC BY 3.0.