Class 8 Physics Some Natural Phenomena Electroscope

It is an instrument used to detect electric charges.A simple electroscope can be constructed as follows.

  • Take a glass container.
  • Insert a metal wire inside it.
  • To the ends of the wire, which are inside the jar, attach 2 metal plates(say aluminium plates).
  • The other end is outside the glass container is connected or brought in contact with charged body.



The electroscope detects charge in the following way:

  • A charged object is brought in contact with the open end of the wire .
  • The charges are transferred via the wire which is a good conductor of electricity.
  • The aluminium plates also get charged and since they are similarly charged, they repel and move away from each other.
  • This confirms the presence of charge on the body.

Grounding & Discharging

If the charged body was brought close to the electroscope and then, we simultaneously touch the metal plates with your hand, then this would cause the charges to flow through your body ( your body is a good condutor of electricity) to the ground. This is called grounding. The plates no longer repel because their charges are 'discharged' to the ground because of grounding.

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