Stationary particle in a laser beam

[Dart82]

Homework Statement

A stationary particle of charge q = 3.0 10-8 C is placed in a laser beam whose intensity is 2.5 103 W/m2.

(a) Determine the magnitude of the electric force exerted on the charge.

(b) Determine the magnitude of the magnetic force exerted on the charge.

Homework Equations

Force on a charge--> F=qE
S = cu
u = (1/2)εo*E^2

The Attempt at a Solution

a.) i am given S and i know c so i can find u by S/c = u.
now that i have u i can solve for E using u = (1/2)εo*E^2.
I multiply E times q to get F.
sounds easy enough and makes sense to me, however i am doing something wrong here huh?

b.) i know that the magnitude will be zero since the charge is stationary.

 

[Meir Achuz]

Looks OK to me.