Point charges in an equilateral triangle

[mbenade]

In an equilateral triangle a positive point charge +q is located at each of the vertices. If a 4th charge is added at the midpoint between one of the sides could this charge be such that the force on it would be zero?

 

[tiny-tim]

Welcome to PF!

Hi mbenade! Welcome to PF!

In an equilateral triangle a positive point charge +q is located at each of the vertices. If a 4th charge is added at the midpoint between one of the sides could this charge be such that the force on it would be zero?

What do you think?

 

[dacruick]

I think everytime tiny tim decides to help someone through with a problem im going to come in behind him and tell the asker all the answers in some feeble and embarrassing attempt to steal his thunder. But hes right...what do you think

 

[mbenade]

my first answer would be no because a forth charge would be needed to cancel out the force on the new point charge by the opposite pt charge, but Im not sure.

 

[tiny-tim]

Hi mbenade!

my first answer would be no because a forth charge would be needed to cancel out the force on the new point charge by the opposite pt charge, but Im not sure.

hmmm … yes, but not very scientific-sounding …

Hint: do any of the charges cancel out (at that midpoint)? ​