Coulumb's Law?

Question

I'm having trouble understanding some of these basic electrostatic priciples and my book isn't much help. I've put them in a true/false format. If I could get at few answers, it would really help me understand this.

A positive point charge +q is placed at point p to the right of two charges, A and B. The net force on the +q charge is found to be zero. Which of the statements below are true?

A-----------B-----------P
++++++++++++++++++++q

True or False -- The magnitude of the charge A must be smaller than B.

True or False -- Reversing the sign of +q to -q would make the force on it nonzero.

True or False -- B must have the same sign as A and be less in magnitude.

True or False -- B must have the opposite sign from A and be less in magnitude.

True or False -- Either A or B must be positive.

Answer 1

1.false(B must be smaller in magnitude)
2.false ( the force directions from B and A wud also be reversed so no net effect)
3.false (if they are of the same sign , then the given initial condition wud not be satisfied)
4.true
5.true

Answer 2

My answers are:

1. false, magnitude on charge A must be larger becuase we have net force equal to zero at point p. Since it is further away, A must have a larger magnitude.

2. False, changing the sign on q should not affect net force.

3. False, A and B must have different signs. One attractive the other repulsive. We cannot tell from the information which is which though.

4. True, look at part 1 and 3.

5. True, one must be positve, look at part 3.

Answer 3

all ur choice r false , the force at p will be 0 only charge A and charge B are opposite in sign and have same magnitude

Answer 4

1. false
2. false
3. false
4. true
5. true