10-40. What is the
electric
field (magnitude and direction) at point D in Figure 10-20 due to the
two
charges? Charges q1 and q2 are -1.21 mC
and +3.40 mC, respectively.
[Ans. 6.0X1014 N/C at 33° relative to +x axis]
The drawing shows the situation as posed in the
problem. The field is wanted at the point D. What test charge do we
imagine
to be placed there to give the direction and magnitude of the field?
(A) a positive
test
charge
(B) a negative
test
charge.