Question

If you have charged an electroscope by contact with a positively charged object, describe how you could use it to determine the charge of other objects. Specifically, what would the leaves of the electroscope do if other charged objects were brought near its knob?

Short answer

If other charged objects were brought near the knob of a positively charged electroscope, the charge of other objects can be determined by observing the motion of the leaves of the electroscope.

Step-by-step solution

Electroscope

An electroscope is a device that is used to determine the presence of a charge on a body.

The electroscope consists of a plate made of a metal knob at the top of a post of metal with leaves made up of thin foils of metal which is hanging from the lower part of the post.

Determination of the charge of other objects

When a positively charged body comes in contact with the knob of the electroscope, the leaves of the electroscope will become positively charged and will spread out.

If another positively charged body is brought near the knob of the electroscope, the leaves will either stay the same or further spread out.

If a negatively charged body is brought near the knob of the electroscope, the negative charges from the body will try to neutralize the positively charged leaves of the electroscope and the leaves will come closer to each other.