Learning goal: to understand the nature of electric fields and how to draw field lines. electric field lines are a tool used to visualize electric fields. a field line is drawn beginning at a positive charge and ending at a negative charge. field lines may also appear from the edge of a picture or disappear at the edge of the picture. such lines are said to begin or end at infinity. the field lines are directed so that the electric field at any point is tangent to the field line at that point.

scattering of light by tiny particles in air to produce the colors we see on sky, is dependent on the following factors:

(i) wavelength of light

(ii) size of the scattering particle  

(iii) distance traveled by light through the atmosphere.

according to rayleigh's law of scattering, the amount of scattering is inversely proportional to the fourth power of its wavelength. shorter the wavelength, greater is its scattering. hence violet/blue light is scattered more than red.

sun's light is a composite light ( visible light) with wavelengths in the range 400 nm (violet) to 700 nm (red). as sunlight passes through our atmosphere, the molecules of air scatter light according to their wavelengths. during sunrise and sunset, the sun's position is below the horizon. hence light from the sun travels a greater distance in the atmosphere when compared to its position a noon.

as sunlight enters the earth's atmosphere, blue light is scattered away and at the end of its journey in the sky, only red and orange wavelengths remain in the beam.

hence at sunrise and sunset, the sky appears reddish orange.

so easy. just google the electromagnetic waves and it’ll pop up.

a skateboard rolling across the street - apex