The principle of the measuring pen (for your reference) :
1. Ohm's law: I=U\/R;
2, the total resistance relationship of the series circuit: R=R1 R2;
3, the structure and characteristics of the measuring pen. Specific instructions are as follows: A. When the measuring pen detects whether A conductor is a live wire or a neutral wire, the current of the measuring pen (that is, the current through the human body)I = the total voltage U added to both ends of the measuring pen and the human body, divided by (\/ equivalent to the fraction line) the measuring pen and the total resistance at both ends of the human body R. B, the lighting circuit, when the measuring wire, There is a voltage U=220V between the fire line and the ground, the resistance of the human body is generally very small, usually only a few hundred to several thousand ohms, and the resistance inside the measuring pen is usually a few megaohms, the current through the measuring pen (that is, the current through the human body) is very small, usually less than 1 ma, such a small current through the human body, no harm to people, When such a small current passes through the neon bubble of the measuring pen, the neon bubble will glow. C, when measuring the zero line, U=0, I=0, that is, no current passes through the neon bubble of the measuring pen, and of course, the neon bubble will not glow. In this way, we can determine whether the live line or the zero line is based on whether the neon bubble is glowing. A few megohm is usually less than 1 MA
The electric shock pen is also called the test pen, which is mainly composed of a metal nib, a very large resistance, a neon tube spring and a metal body at the end of the pen.
When used, the nib contacts the wire, and the hand contacts the metal pen end, then the human body and the large resistor are connected in series in the circuit. If the nib contacts the live wire, when the person is standing on the ground, the large resistor in the human body and the electroshock pen is connected between the live wire and the ground wire, and there is a voltage of 220v between them, the circuit path, there will be a small current passing through the resistor and the human body, and the neon tube will glow; If the nib is in contact with the zero line, there is no voltage between the zero line and the ground, so no current passes through the test pen and the human body, the neon tube will not glow. This will determine which is the fire line and which is the zero line.
△ The working principle of the pen test pen: the test pen has a neon tube, filled with neon, and two metal electrodes at both ends. When the current flows from one electrode to the other, neon will emit red light. Pen type tester...