Question

a.)Find the magnitude of the net electric field these charges produce at point A.
the answer to this is E = 8740 N/C.
my question is in this question

b.)What would be the magnitude of the electric force this combination of charges would produce on a proton at A?

the answer is 1.40*10^-15 N and I think you can get this by using the F = qE so F = 8740*E formuala but i dont understand how you get the E. pleaseexplain and show steps.

Answer 1

dear, your basic concepts are not clear.
f=q*E
q=1.6*10^-19 as its a proton

E=Q/r^2 in magnitude. the direction of the forces can be determined by seeing the charges.

at the point of proton(positive charge) the forces by both the -ve charges is attractive. the net force can be calculated by simple vector addition.

for the charge -6.25nC

f1= 6.25*(1.6*10^-19)/(25-10)^2

similarly can find f2

then subtract them to find the net force.