Calculate Electric Field Between -30 & +50 uC Charges

[pat666]

Homework Statement

Two point charges, -30 and +50 , are separated by a distance of 17.0 cm . (micro couloumbs)

Express your answer to two significant figures and include the appropriate units.

Homework Equations

E=kq/r^2

The Attempt at a Solution

E1=9E9*30E-6/.085^2= 3.73*10^7
same for E2 =6.23*10^7
E2-E1=2.5E7 N/C
Really not sure on how to do this, i was just doing what seemed logical to me but the procedure could be entirely wrong. ( I am sure that my answer is wrong)

 

[rl.bhat]

If you are finding the net field at the center of the line joining the charges, then the electric fields at the center are in the same direction. So the net field at that point is E = E1 + E2.

 

[pat666]

thanks, i now have the correct answer but part to of the question is What is the direction of the electric field at a point halfway between the two charges?

I think that it would be toward the positive charge since it is bigger?

 

[Dadface]

E is defined as the force acting on unit positive charge.

 

[pat666]

so it would actually be toward the negative charge since the positive charge would repel it?

 

[Dadface]

Correct

 

[pat666]

thanks dadface