practice testMultiple Choice

Practice Test

Question 7 • Physics

A point charge is used to determine the electric field around a charged particle. Why is it necessary that the point charge does not affect the position of the charge being tested?

Answer

Electric fields are inversely proportional to the square of the distance, so any change in position changes the field.

Electric fields are directly proportional to distance, so any change in position changes the field.

The amount of charge will decrease if the charged particle moves closer to the point charge, so any change in position changes the field.

The amount of charge will increase if the charged particle moves closer to the point charge, so any change in position changes the field.

Explanation

The electric field of a point charge depends on distance according to an inverse-square relationship: E = kQ/r². If the test charge shifts the charged particle, the distance r changes, which changes the field being measured. Choice A correctly describes why the particle’s position must remain unchanged.

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