Consider regions close to the surface where the plane of current appears of infi

Question

Consider regions close to the surface where the plane of current appears of infinite extent. Plane electromagnetic waves travel away from the sheet in both the positive and negative y directions.

(a)      In what axis will be the electric field vector?

(b)     In what axis will be the magnetic field vector?

(c)     Write down an expression for the electric field component of the wave travelling in the positive y direction. Use Ampere’s Law to make an estimate for the magnitude of the wave. Consider the signs of the waves.

  d)   Write down an expression for the magnetic field component of the wave travelling in the opposite direction.

e)  Consider the wave travelling in the positive y direction. What is the Poynting vector for this wave? What is the intensity of this wave?

Explanation / Answer

(a) z axis

(b) x axis

(c) Ez = Eo sin(t - ky)

(d)& (e) Bx = Bo sin(t - kx)

The Poynting vector:

S = (1/µo) BxE

but E = B c,

S = (eo/µo) E² = (eo/µo) Eo² sin(t - ky)²

Wave intensity: I

I = S* Area = ((eo/µo) Eo²) r²

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.