Point charges, midpoint zero or non zero?

[rcmango]

Homework Statement

Point charges +q and -q are placed at +50 cm and -50 cm on the x-axis, respectively. Is the electric field at the origin (halfway between the charges) zero or nonzero? If nonzero, which direction does it point?

Homework Equations

The Attempt at a Solution

Well I know the charges will be attracting each other because they are opposite in polarity. I'm not sure if the electric field will be zero or non zero. I do know that if the charges were the same polarity, then the midpoint in the middle would both be zero. Please help me figure this one out completely.

 

[NascentOxygen]

Point charges +q and -q are placed at +50 cm and -50 cm on the x-axis, respectively. Is the electric field at the origin (halfway between the charges) zero or nonzero? If nonzero, which direction does it point?

Use the superposition principle. Google "electric field" and "superposition".

 

[kuruman]

Place a positive test charge at the origin. If the net Coulomb force on the test charge is zero, the electric field is zero; if the net Coulomb force is not zero, then the electric field is not zero and point in the same direction as the net Coulomb force.

 

[HallsofIvy]

Homework Statement

Point charges +q and -q are placed at +50 cm and -50 cm on the x-axis, respectively. Is the electric field at the origin (halfway between the charges) zero or nonzero? If nonzero, which direction does it point?

Looking at the +q charge at +50 cm only, a negative charge would feel a force toward it, in the positive direction (and a positive charge in the negative direction). Looking at the -q charge at -50 cm only, a negative charge would feel a force away, in the positive direction (and a positive charge in the positive direction). The two forces add, they do not cancel.

Homework Equations

The Attempt at a Solution

Well I know the charges will be attracting each other because they are opposite in polarity. I'm not sure if the electric field will be zero or non zero. I do know that if the charges were the same polarity, then the midpoint in the middle would both be zero. Please help me figure this one out completely.