Coulomb's Law

Practice

practice problem 1

Compute the magnitude of the electrostatic and gravitational forces between …
  1. an electron and proton in a hydrogen atom (the radius of the electron's orbit is about 53 pm)
  2. two protons in a helium nucleus (the separation between them is about 1.2 fm)
  3. the earth and the moon

solution

  1. Answer it.
  2. Answer it.
  3. Answer it.

practice problem 2

If the moon were held in its orbit by an electrostatic rather than gravitational force …
  1. What quantity of charge would be needed?
  2. How many elementary charges is this?

If all of the charge came from the separation of hydrogen atoms into electrons and protons …

  1. What mass of hydrogen would be required?
  2. How many liters of H2 gas at STP would be required?

solution

  1. Answer it.
  2. Answer it.
  3. Answer it.
  4. Answer it.

practice problem 3

Given three charges in a standard coordinate system, calculate the magnitude and direction of the net electrostatic force on each.
  1. +10 μC at (0 m, 0 m)
  2. −20 μC at (0 m, +3 m)
  3. +25 μC at (−4 m, 0 m)

solution

  1. Answer it.
  2. Answer it.
  3. Answer it.

practice problem 4

Write something completely different.

solution

Answer it.