Question

The rms electric field of an electromagnetic wave increases from 307 to 921 N/C.

(a) Determine the wave intensities for the two values of the electric field.

(b) What is the rms magnetic field associated with each electric field?

(c) Determine the wave intensity for each value of the magnetic field.

(a) S1 = 249.99 Correct: Your answer is correct. Correct: Your answer is correct.

S2 = 2250 Correct: Your answer is correct. Correct: Your answer is correct.

(b) B1 = 1.02e-6 Correct: Your answer is correct. Correct: Your answer is correct.

B2 = 1.02e6 Incorrect: Your answer is incorrect. Correct: Your answer is correct.

(c) S3 = 247.67 Correct: Your answer is correct. Correct: Your answer is correct.

S4 = -247.67 Incorrect: Your answer is incorrect. Correct: Your answer is correct.

I just need help with B2 and S3

Answer 1

step:1

the electric field in rms =>E1=307 N/c E2=921 N/c

now we find the intensity of two values

intensity S1=8.84*10^-12*(307)^2*3*10^8=249.99W/m^2

intensity S2=8.84*10^-12*921^2*3*10^8=2250 W/m^2

step:2

now we find the magnetic field

magnetic field in rms =>B1=307/3*10^8=1.02*10^-6 T

magnetic field in rms =>B2=921/3*10^8=3.07*10^-6 T

step:3

now we find the intensity in magnetic field

S3=(1.02*10^-6)^2*10^8*3/9*10^9

=346.8*10^-13 W/m^2

S4=(3.07*10^-6)^2*3*10^8/9*10^9

=3.142*10^-13 W/m^2