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03 Jul, 2021 02:46 PM

What is the amplitude of the oscillating electric field?

A microwave oven operates at 2.4 GHz with an intensity inside the oven of 2800 W/m^2. What is the amplitude of the oscillating electric field? What is the amplitude of the oscillating magnetic field?

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HA
03 Jul, 2021 02:47 PM

Definition of Intensity: I = P/A

For an electromagnetic wave with electric field amplitude, E_0, and magnetic field amplitude, B_0

I = (1/2)*C*ℰ_0*(E_0)^2 = (1/2)* (C/u_0)*(B_0)^2

(E_0)^2 = C*B_0

Therefore starting with Part B:

I = (1/2)* (C/u_0)*(B_0)^2

(B_0)^2 = 2*u^2*I/C

(B_0)^2 = 2*(4pi*10^-7)*2800/(3*10^8)

(B_0)^2 = 2.3457*10^-11

Hence, B_0 = sqrt(2.3457*10^-11) = 4.8*10^-6 T

Then for Part A:

E_0 = C*B_0

E_0 = (3*10^8)(4.8*10^-6)

Therefore, E_0 = 1452.98 which is approximately 1500 V/m

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