the metals wires in the bottom part of the electroscope are earthed give reason
Answers
Explanation:
This is an instrument used for detecting and measuring static electricity or voltage (mainly to detect small charges).
A metal disc is connected to a narrow metal plate and a thin piece of gold leaf is fixed to the plate. The whole of this part of the electroscope is insulated from the body of the instrument.
A glass front prevents air draughts but allows us to watch the behaviour of the leaf.
When a charge is put on the disc at the top, it spreads down to the plate and leaf. This means that both the leaf and plate will have the same charge. Similar charges repel each other and so the leaf rises away from the plate -
NOTE : the bigger the charge the more the leaf rises.
The leaf can be made to fall again by touching the disc - when we will earth the electroscope. An earth terminal prevents the case from becoming live. The electroscope can be charged in two ways
(a) by contact - a charged rod is touched on the surface of the disc and some of the charge is transferred to the electroscope. This is not a very effective method of charging the electroscope
(b) by induction - a charged rod is brought up to the disc and then the electroscope is earthed, the rod is then removed.
The two methods give the gold leaf opposite charges.
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