Why Ebony Stick Attracts Paper

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Why Ebony Stick Attracts Paper
Why Ebony Stick Attracts Paper

Video: Why Ebony Stick Attracts Paper

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School experience shows that an ebony stick that is rubbed against fur begins to attract small objects like pieces of paper. This is facilitated by the action of the Coulomb forces.

Ebony sticks
Ebony sticks

Why is this happening?

Ebonite is a highly vulcanized rubber with a high sulfur content, dark brown or black in color. Thus, we can say that ebonite is something like a hardened mixture of rubber and plastic and, of course, is a dielectric, that is, it practically does not conduct current.

If you just take an ebony stick and bring it to the paper, nothing will happen. But if you first rub it on fur or silk, then pieces of paper, trickles of water, hair, etc., as if by magic, will be attracted to the stick.

The fact is that when the ebony stick and fur rub against each other, the area of ​​their contact increases, the charges are distributed, due to which the ebony stick acquires a charge, which in this case will be negative, and the fur - a positive charge (in the case of paper and glass and with paper everything is exactly the opposite). When the stick is brought to the paper, free electrons rush to the scraps of paper, due to which the initially neutrally charged object on the one hand acquires a positive charge, and on the other - negative. And the positive sides of the pieces of paper are attracted to the negatively charged stick due to the action of the Coulomb forces.

By itself, the stick will not attract the paper, because compared to the Earth, the force of attraction between the stick and the paper is clearly less than between the paper and the planet. But in the case of an electrified ebony stick, a force arises that is clearly greater than the gravitational one.

When the stick is brought up to small pieces of paper, one of the sides of the pieces of paper acquires a positive charge. Due to the fact that unlike charges due to Coulomb forces are attracted, the objects themselves, which have charges, rush to each other.

How to make it more interesting?

The ebony stick experience can be made more interesting. For example, you can take an additional small steel rod that conducts electricity, touch it on one side with an ebonite stick, and bring the other side to pieces of paper. The paper will again begin to be attracted, but this time to the steel rod.

This is due to the fact that the rod, being a conductor, receives the same charge as the rod. If you take a charged steel and uncharged ebony stick and swap them, then nothing will happen. This is due to the dielectric properties of ebonite - the rod simply will not accept the charge from the steel rod.

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