To demonstrate Amperes Law that when electricity is passed through a magnetic field it produces an electric field, which in this apparatus can be observed by the deflection of the needle. Consists of two poles of magnets mounted on a stand, on which swings a pointer. When electric current is passed the pointer deflects on one side and when the current is reversed it deflects in the opposite direction. Operates on 3-6 Volts DC.
Measurements are approximate.