A sinusoidal electromagnetic wave is propagating in vacuum. (a) At a given point and at a particular time the electric field is in the +x direction and the magnetic field is in the -y direction. What is the direction of propagation of the wave?
(b) At the above point the intensity of the wave is 0.45 W/m
2. What is the electric field amplitude at this point? (NOTE: μo=4π×10−7.Tm/A and c=3.00×108m/s)

the electric field is a “force field” around a charged object that illustrates the direction the electric force would push an imaginary 

b.

explanation:

as we know our atmosphere or air have different levels. every level has other gasses, and every gas has another permeability. when the light comes from lower permeability to higher permeability, it changes its direction. so that means that when the light comes from the moon to the earth, it changes it's direction many more times. it basically means that the shape of the light part of the moon is changed on the earth.

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