Practice question · Numerical answer
Two point charges exert a force of 36 N on each other. If the separation is tripled and the charges are unchanged, what is the new force, in newtons?
Hints
- Coulomb's law falls off with the SQUARE of the distance.
- Tripling the distance divides the force by 3 squared.
Show the answer
4
Why
, so tripling r divides the force by 9: N. Dividing by 3 instead of 9 gives 12 N, the standard error, the inverse-square law punishes distance far harder than intuition expects.
Practise Electromagnetism
The app has 6 more questions on this lesson, and keeps your place in the course. Mathematics I is free to start.
More questions on Electromagnetism
- A bird stands on a high-voltage line unharmed, and a person touching the same line would be killed. What is…
- Select every statement that is TRUE about electromagnetism.
- Coulomb's law and Newton's gravitation share the inverse-square form, but only one of the two forces can…
- Faraday's law says a CHANGING magnetic field induces a voltage, and a steady one induces nothing. Why does…
- Two point charges attract with a force of 8 N. One charge is then doubled and the separation is also doubled.…
- Sort each pair of charged objects by the direction of the force between them.