Two point charges `q_(A)=3muC` and `q_(B)=-3muC` are located 0.2 m apart in vacuum.
a. What is the electric field at the mid point O of the line AB joining the two charges?
b. If a negative test charge of magnitude `1.5xx10^(-9)C` is placed at this point, what is the force experienced by the test charge?

Explanation

Given :
`q underset(A)=3muC, q underset (B)=-3muC,r=20" " cm " 0.2"" "m,E_(R)=?,F=?`

we have E= `(1)/(4 pi epsilon_(@))(2)/(r^(2))` Electric intensity dueto `q_(A)` on P `E_(A)=(1)/(4 pi epsilon_(@))(q_(A))/r^(2)`
`E underset (A)=(9x10^(9) x3x10^(-6))/((0.1))`
`=(27x10^(3))/((0.1)^(2))=(27x10^(3))/(0.01)`
`E underset(A)=2700x10^(3)NC^(-1)=2.7x10^(6)NC^(-1)`
`E underset(A)`
`E underset(B)=2.7x10^(6)NC^(-1)` Resultant field, `E underset(R)=E underset(A) + E underset(B)=2.7x10^(6)+2.7x10^(6)`
`E underset(R)=5.4x10^(6)N//` Calong AB