Question

8. An oxygen ion consists of 8 protons, 8 neutrons, and 10 electrons. Determine the net charge on this oxygen ion in coulombs.

9. Two charged particles separated by 60 cm attract each other with a force of 1.8 N. One particle has a charge of -83 μC. What is the sign and magnitude of the other charge?

Answer 1

8) Number of electron = 10

number of protons= 8

number of neutron = 8

charge on each proton = 1.6*10-19 C

charge on each electron = -1.6*10-19 C

charge on each neutron = 0 C

Total charge in electron ion = 8*1.6*10-19 + 10*(-1.6*10-19)+8*0 = -3.2*10-19 C

This is the required answer

9)

Separation between charges = r = 60 cm = 0.6 m

Force of attraction between the charges = F = 1.8 N

Charge on one particle = Q1 = -83*10-6 C

Let the magnitude of the other charge be Q2

Per Coulomb's law,

F = k*Q1*Q2/r2 , where k = 9*109

Or , 1.8 = 9*109*83*10-6*Q2/0.62

Q2 = 0.867*10-6 C = 0.867 C

Since the force is attractive, the sign of Q2 will be opposite of Q1.

Therefore Q2 = + 0.867 C

This is the required answer