Is the signal measured by the induction test pencil a magnetic field or an electric field?
Oersted's experiments showed that there is a magnetic field around a current-carrying wire as well as around a permanent magnet. Oersted's experiment revealed a very important essence - there is a magnetic field around the current, and the current is generated by the directional movement of the charges, so the magnetic field around the current-carrying wire is essentially generated by the moving charges. This phenomenon was first discovered by the Danish physicist Oster in July 1820 through experiments.
When the circuit is in a normal state, Q1 forms a leakage current due to the floating gate, there is no current flowing into the base of Q2, and Q3 is in an off state. When the induction board is close to the AC power supply of 220V or above, because the power supply will form an alternating electric field around, the induction board will induce the corresponding alternating voltage and add it to the gate of Q1. When the induction voltage on the induction board is negative, Q1 Cut off, the V voltage is added to the base of Q2 through R1 and Q4, Q2 is turned on, and Q3 emits light.
According to my analysis, the induction test pen, the induction signal is: the alternating electromagnetic field around the alternating current (generating an induced electromotive force, inputting a direct current circuit, and generating a current). It becomes a unidirectional current through the diode, then amplified by the triode, and finally reaches the light-emitting diode.
