Question

26.1) How many electrons must be added or removed to an uncharged object in order to give the object a charge of:

(a) -1.1 x 10^-14 C

(b) 8 x 10^-19 C

27.2 ) Two charged metal spheres are fixed in place 1 m apart.

Sphere A has a charge of + 1 mC while sphere B has a charge of + 2 mC.

(a) What is the electric force on sphere A (in N) ?

(b) What is the electric force on sphere B (in N) ?

The charges on each sphere are altered such that sphere A now has a charge of + 2 mC while sphere B has a charge of + 1 mC.

Answer 1

(1) In order to understand charge added or removed, you have to know about positive and negative charge.

Positive charges are carried by protons and negative charges are carried by electrons. So, if there are more protons than electrons this means that it has positive charge and if there are more electrons then it has negative charge and if they are equal, it will be neutral.

And, the number of electrons can be calculated as,

where, e is the charge of electron

n is the number of electrons

q is total charge

(a) Given charge is negative that means it has more electrons, so for getting this charge, we have to add

electrons from the object.

(b) Given charge is positive that means it has less number of electrons, so for getting this charge, we have to remove

electrons from the object.