Question

C) An electroscope has an initial charge. As an object of unknown charge polarity
approaches the sphere of the electroscope, the leaves of the electroscope come closer
together. When the same object then comes in contact with the sphere, the leaves
completely collapse together briefly and then spread apart again. When a second object
that is negatively charged comes close to the sphere of the electroscope, the leaves come
closer together.

a) What is the polarity of charge of the unknown object?
b) What is the polarity of the initial charge of the electroscope?

Answer 1

Solution : according to second situation when the negative charged object is brought near by the electroscope then its leaves come colser which suggest that it must have positive charge In second time . So the object which was brought near the electroscope first time should have positive charge .

When you bring a similar charge to electroscope it leaves diverge while on bringing opposite charge it leaves converge. It occurs due to induction.

So in first case when the positive charged object was brought to near the electroscope it had negative charge.

Hence.

Charge on object = positive

Charge on electroscope initially = negative