Question

. Determine the gravitational attraction between the pro-
ton and the electron in a hydrogen atom, assuming that
the electron describes a circular orbit with a radius of
0.53 x 10 m (mass of proton = 1.67 x 10-27 kg
mass of electron = 9.1 x 1031 kg)
-10​

Answer 1

By the end of this section, you will be able to:

State Coulomb’s law in terms of how the electrostatic force changes with the distance between two objects.

Calculate the electrostatic force between two charged point forces, such as electrons or protons.

Compare the electrostatic force to the gravitational attraction for a proton and an electron; for a human and the Earth.

Coulomb’s law calculates the magnitude of the force F between two point charges, q1 and q2, separated by a distance r. In SI units, the constant k is equal to

k

=

8.988

×

10

9

N

⋅

m

2

C

2

≈

8.99

×

10

9

N

⋅

m

2

C

2

The electrostatic force is a vector quantity and is expressed in units of newtons. The force is understood to be along the line joining the two charges. (See Figure 2).