Suppose a speck of dust in an electrostatic precipitator has 1.×10^12 protons in it and has a net charge of –5.00 nc (a very large charge for a small speck). how many electrons does it have?

Explanation:

The net charge is given by the sum of the charges of the protons and of the electrons:

where we have

is the net charge

is the number of protons

is the charge of one proton

is the number of electrons

is the charge of one electron

Solving the equation for , we find the number of electrons:

iron would move it is magnetic there is a mag field around the current in the wire

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.