Four charges, equal to -Q are placed at the four corners of a square and a charge 'q' is at its centre. If the system is in equilbrium, the value of q is -
a) -Q(1+2 sqrt 2)/4 b)Q(1 + 2 sqrt 2)/4
c)-Q(1+2 sqrt 2)/2 d)Q (1 + 2 sqrt 2)/2

Question

Four charges, equal to -Q are placed at the four corners of a square and a charge 'q' is at its centre. If the system is in equilbrium, the value of q is - 
a) -Q(1+2 sqrt 2)/4  b)Q(1 + 2 sqrt 2)/4  
c)-Q(1+2 sqrt 2)/2   d)Q (1 + 2 sqrt 2)/2

vincent-lyon.fr · Answer

q charge is always in equilibrium.

-Q charges are attracted to q and repelled by the other 3 -Q charges.

Draw the square and work out the net force exerted by the 3 -Q charges on the fourth one.

vincent-lyon.fr · Answer

Right back! So what are you up to?
2 of the answers are obviously impossible.

anonymous · Answer

Hey, thanks...i got it..:D