1 big solenoid coil, 5 small coils at different cross section and number of windings, 1 signal generator, 1 multimeter, connection cables,oscilloscope:extra.Technical Information
According to Faraday's law, the magnetic flux (magnetic fieldxarea) induces a voltage in coils if it changes in time. This is possible if only magnetic field changes in time (AC signals) or the area changes (electric motors) while magnetic field is kept constant (usually by permanent magnets). If the current in a big coil changes according to the equation: I=I0Sin(2πft) where f is the frequency, the small coils placed in the big coil produce voltages in order to create an opposing magnetic field to eliminate the original field created by the big coil.
This can only be done by allowing some currrents to flow across the windings of small coils. Induced voltage is given by: V = Ldi/dt =V0Cos(2πft). Although this equation is a function of the applied frequency, the magnitude (V0) of this signal is dependent on the number of windings, the length and the cross section of small coils. When any of these properties increases, the magnitude of induced voltage also increases. The measurements are performed by a multimeter for the frequencies up to 10kHz. The purpose is to show the dependence of induced voltage on these properties..