You and a friend are spending the weekend making up missed lab experiments. you are on to second - semester material and are studying the electrostatic interaction of two charges. you notice that two charges are exerting a certain force on one another. if the distance between two electric charges doubles, then the force they exert on each other changes by how much?
2 times as large
4 times as large
1/4 as large
1/2 as large

1/4 as large  

Explanation:

Lets take

q₁ and q₂ are the charge on the particle and d is the distance between them.

We know that electrostatics between two particle given as

When distance become double d'= 2 d

So new force F'

It means that force will become one forth of initial force.

So answer is 1/4 as large .

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.

causes

fossil fuels burn

cities become more industrialized

human population grows worldwide