Answer
The magnitude of the force is $~~0.245~N$
Work Step by Step
We can find the electrostatic force in unit-vector notation:
$F = q~E$
$F = (8.00\times 10^{-5}~C)~(3000~\hat{i} - 600~\hat{j})~N/C$
$F = (0.240~\hat{i} - 0.048~\hat{j})~N$
We can find the magnitude of the force:
$F = \sqrt{(0.240~N)^2+(0.048~N)^2}$
$F = 0.245~N$
The magnitude of the force is $~~0.245~N$
