Question

Is this correct: Like charges repel and unlike charges attract?

Answer 1

yes it is

Answer 2

that's right!
+ + or - - repel
+- or -+ attract

Answer 3

The electrostatic Coulomb force \(\mathbf F\), between charges \(q\), and \(Q\), a distance \(r\) apart,
where \(\hat{\mathbf r}\) is the unit vector pointing from one charge to the other, and \(K\) is the coulomb constant;\[\mathbf F = K\frac{qQ}{r}\hat{\mathbf r}\]
When the charges have the same sign, their product will be positive and hence the force will be positive (attractive),
When the charges have opposite sign, their product will be negative (repulsive)