Amplitude of oscillating magnetic field

[Roodles01]

N = 1/2 E₀ √(ε/μ)
so
E₀ = √2*N*(ε/μ)
where the value of ε/μ is 376.7Ω

I have a similar question to this, below, regarding amplitude of an oscillating magnetic field.
Yes, I'd like the answer, but am initially stuck deciding whether the mW is milli- or mega-

Homework Equations

A laser found in supermarket checkout scanners emits light in a 1.1 mm diameter beam with a power of 1.3 mW.

Part A
What is the amplitude of the oscillating electric field in the laser beam?
Express your answer to two significant figures and include the appropriate units.
=

Part B
What is the amplitude of the oscillating magnetic field in the laser beam?
Express your answer to two significant figures and include the appropriate units



Part A
N = 1/2 E₀ √(ε/μ)
so
E₀ = √2*N*(ε/μ)
where the value of ε/μ is 376.7Ω
E₀ = √2*10³*376.7Ω
= 877.0 V m^-2

Not sure how to find the amplitude of the oscillating magnetic field though.

Any help gratefully received.

 

[BruceW]

I'm not sure what N is supposed to mean? Also you've written: "where the value of ε/μ is 376.7Ω" But that should have units of ohm squared.