Which is an example of gaining a static charge by conduction? a) rubbing a balloon against your hair. b) shuffling your shoes across a carpet. c) bringing a charged rod near an electroscope. d) touching your car on a cold day and getting a shock.

 D) Touching your car on a cold day and getting a shock.

Explanation:

Ok, there are 3 forms of generating static charge:

Friction: This is one of the most common examples, the static charge is generated as you rub an object with another, and in the process, one of the objects "steals" electrons of the other object, and in this way generates a static charge. Examples of this are option A and B.

Induction: You have a charged object, and you put it near another object that may steal electrons. In this way you are "inducing" statical charge in the other object; an example of this is option C.

Conduction: In this case, you "connect" two objects and thanks to this connector, electrons of one object (the most charged one) can flow to the other. For example, in option D "Touching your car on a cold day and getting a shock." the car and you are the objects, and when you touch the car, your finger is the connector between you and the car that allows the conduction to happen.

50 inches should be the resultant vector

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.