Question

Consider a monochromatic electromagnetic plane wave propagating in the x direction. At a particular point in space, the magnitude of the electric field has an instantaneous value of 941 V/m in the positive y-direction. What is the instantaneous magnitude of the Poynting vector at the same point and time? The speed of light is 2.99792 x 108 m/s, the permittivity of free space is 8.85419 x 10-12 C2/N/m2 and the permeability of free space is 47 x 10-7 T N/A.
What is the direction of the instantaneous magnetic field?
1. B = - 2.
2. B = +î.
3. B = +j.
4. B = - j.
5. B = +k.
6. B = -k.
7. The magnetic field vector does not have an instantaneous direction.
What is the direction of the instantaneous Poynting vector?
1. Ŝ= -î.
2. Ŝ= -k
3. The Poynting vector does not have an instantaneous direction.
4. Ŝ = tî.
5. Ŝ = +Î.
6. Ŝ= -Î.
7. Ŝ= +ê.

Answer 1

Answer:

a)   S = 2.35 10³   J/m²2 ,  

b)and the tape recorder must be in the positive Z-axis direction.

the answer is 5

c) the direction of the positive x axis

Explanation:

a) The Poynting vector or intensity of an electromagnetic wave is

          S = 1 /μ₀ E x B

if we use that the fields are in phase

          B = E / c

we substitute

         S = E² /μ₀ c

let's calculate

        s = 941 2 / (4π 10⁻⁷  3 10⁸)

        S = 2.35 10³   J/m²2

 

b) the two fields are perpendicular to each other and in the direction of propagation of the radiation

In this case, the electro field is in the y direction and the wave propagates in the ax direction, so the magnetic cap must be in the y-axis direction, and the tape recorder must be in the positive Z-axis direction.

the answer is 5

C) The poynting electrode has the direction of the electric field, by which or which should be in the direction of the positive x axis