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(2) Imagine that a sinusoidal electromagnetic wave has an electric field that ha

ID: 1262910 • Letter: #

Question

(2) Imagine that a sinusoidal electromagnetic wave has an electric field that has an amplitude of 300 N/C arid points parallel to the yz plane along a line 300 from the z axis toward the y axis. Imagine that we write this wave as a sum of horizontally and vertically polarized waves. (a) What are the values of the amplitude of cadi of these different polarizations? (Hint: We are writing our electric field in this form: E = E cos(kx - wt)3 + E cos(kx - wt)k) (b) At an instant when the z?component of E is positive, what are the magnitude arid direction of B?

Explanation / Answer

PART A:

Ey = 300 N/C * sin 30

Ey = 150 N/C   [ANSWER, amplitude along y]


Ez = 300 N/C * cos 30

Ez = 259.9 N/C   [ANSWER, amplitude along z]

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The magnitude of the B field is always |E|/c.   [ANSWER]

The wave travels along the + x direction as well can tell from the equation.

Thus, as the B field is always perpendicular to the E field, we can tell it has direction 30 degrees from the positive y axis towards the -z axis. [ANSWER]