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 I am going to come in behind him and tell the asker all the answers in some feeble and embarrassing attempt to steal his thunder. But he's 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 I am 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 I am not sure.

hmmm … yes, but not very scientific-sounding …

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