Why is the live wire always on when using the electric test pen?
The positive half-cycle current flows from the live wire to the neutral wire, and the negative half-cycle flows from the zero wire to the live wire. Why does the live wire always light up when using an electric test pen?
Use the electric test pen to measure the live wire is bright because the voltage of the live wire to the ground is 220V. When measuring, the live wire passes through the resistance in the electric pen and grounds through the human body. At this time, there will be current flowing, so the light will be on. The neutral line has a voltage of zero volts to the ground, because the neutral line itself is connected to the ground, and it is at the same potential as the ground you are in, so there is no potential difference and no current can be formed, so naturally it will not light up.
The reason why the neutral line is zero is because it is grounded, and the specified potential of the earth is zero, so the natural potential of the neutral line is zero. This is also the reason why the human body will not get an electric shock when standing on the ground and grabbing the neutral wire.
The neutral line is the line drawn from the neutral point of the transformer. It is the return line from the live wire to the electrical appliance. The ground wire in is the protective earth where your home is located. Because the earth also has resistance, sometimes the neutral line in the home will also be charged, but the voltage is very small and will not cause personal danger.
The potential of the live line in the positive half cycle is higher than the zero line, and the potential of the live line in the negative half cycle is lower than the zero line. The water flows to the lower place, and the current is the same. Here we need to correct a misunderstanding. Many people think that the current can only flow from the positive pole to the negative pole. In fact, the current also flows from the positive pole to the negative pole. Positive pole with high potential flows to positive pole with low potential
The potential mentioned here may not be understood by the person who asked this question, and it can also be understood as voltage. In fact, it is not the same concept. Voltage is a potential difference. There are two reservoirs, one is 100 meters (potential) and the other is 150 meters (potential), then their height difference (voltage) is 50 meters. If the two reservoirs are connected, the high water will flow to the low one. If both are 150 meters (potential) ) would be impossible to flow (zero voltage), even if their height (potential) is high
If you understand the above, the potential of the zero line is assumed to be the surface of the well, and the height is fixed. The live line is a bucket filled with water, and the height is variable. When the bucket is above the surface of the well, the water will flow to the surface of the well, otherwise the water on the surface of the well flow to bucket
Why does the test pen light up on the live line and not on the neutral line? It is because the top of the test pen needs to be connected to the human body and then connected to the earth, and the neutral line is also connected to the earth. They have the same potential
