A point charge in front of a metal sheet

Electricity and Magnetism Level 2

A point charge $Q$ is placed in front of a neutral sheet of metal.

What can be said about the force of interaction between them?

They will attract each other They will repel each other They will not apply any force on each other

2 solutions

Rohit Gupta
Jan 16, 2017

Relevant wiki: Charge and Electric Fields

Metal contains large number of free electrons that move freely inside its bulk. When a charge particle is placed in front of a metal sheet, the electrons in the metal redistribute themselves. If the charge placed $Q$ is a positive charge then the electrons in the metal will accumulate on the surface nearer to the charge and an equivalent positive charge will appear on the other side.

As, the opposite charges are closer, therefore, $\boxed{\text{they will attract each other}}$ .

Note: A similar thing would happen if the charge $Q$ is assumed as negative.

But isn't the electric field produced by an infinitely large sheet independent of distance? I think that the non uniformity of charge distribution is the cause.

Srihaas S - 4 years, 4 months ago

Yes, the field created will be independent of distance from the sheet if the charge on the sheet is uniformly distributed.

Rohit Gupta - 4 years, 4 months ago

@Rohit Gupta Can you add the concept of charge mirroring too?

Kartik Sharma - 4 years, 4 months ago

Raven Herd
Sep 15, 2017

When a charge q is kept in front of a metal sheet , equal and opposite charge is induced on the side facing the charge as free electrons inside the metal sheet rearrange themselves accordingly. And since opposite charges attract thus the answer.

A point charge in front of a metal sheet

2 solutions

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