An electroscope is a device which is used to find if an object is
$(a)$. charged
$(b)$. magnetic
$(c)$. free of cracks
$(d)$. hot

AcademicPhysicsNCERTClass 8

We know that like charges attract and unlike charges repel. This principle can be used to determine whether a charged object is positive or negative. The electroscope is initially charged by a known body (say positively charged body) and then the body is removed. Next, the body under test is brought in contact with the metal cap. If the leaves diverge further, the body has a same charge(positive) and if the leaves come closer to each other, the body has opposite charge(negative). Similarly, if an electroscope is charged by negatively charged body, the opposite will happen.

So, option $(a)$ is correct.

Updated on 10-Oct-2022 13:29:32