The structure of traditional electric measuring pens is very simple, consisting of high resistance resistance, neon bubbles, springs, and pen caps. The neon bubbles do not emit light under low voltage and usually only light up at 100V or above. It is difficult to damage them unless they are hit.

There are various resistance values for high resistance resistors. Theoretically, a resistance value greater than 500k ohms can meet the demand. However, we hope that the larger the resistance value, the better. Of course, it cannot be infinitely large, so it is an open circuit. When measuring charged objects, it does not emit light, which can easily lead to misjudgment. Therefore, the electric pen needs to be regularly checked and maintained.

A measuring pen with a resistance lower than 500k ohms can cause a tingling sensation when measuring charged objects. If the resistance value is lower, it is equivalent to touching the live wire with your hand, and the consequences are very serious.