Flemings Left and Right Hand Rule Apparatus.
Comprises a square bobbin with 75mm sides wound with 150 turns of enameled copper wire 0.41mm dia. Bobbin is supported by 350mm long wires terminated with terminals on a horizontal arm which is attached to a vertical rod on a wooden base.
(Wikipedia excerpt:…Fleming’s left-hand rule for electric motors is one of a pair of visual mnemonics, the other being Fleming’s right-hand rule (for generators). They were originated by John Ambrose Fleming, in the late 19th century, as a simple way of working out the direction of motion in an electric motor, or the direction of electric current in an electric generator. When current flows through a conducting wire, and an external magnetic field is applied across that flow, the conducting wire experiences a force perpendicular both to that field and to the direction of the current flow (i.e they are mutually perpendicular).
A left hand can be held, as shown in the illustration, so as to represent three mutually orthogonal axes on the thumb, fore finger and middle finger. Each finger is then assigned to a quantity (mechanical force, magnetic field and electric current). The right and left hand are used for generators and motors respectively…..” ).