Asolenoidal coil with 21 turns of wire is wound tightly around another coil with 350 turns. the inner solenoid is 25.0 cm long and has a diameter of 2.50 cm . at a certain time, the current in the inner solenoid is 0.120 a and is increasing at a rate of 1700 a/s. for this time, calculate;

(a) the average magnetic flux through each turn of the innersolenoid;
(b) the mutual inductance of the two solenoids;

A) We need to calculate the Magnetic flux of a Solenoid,

Where B is the magnetic field and A the Area.

Here \mu_0 is the permeability constant, I the current and N number of turns.

Replacing we have,

B) We calculate the mutual inductance, so

c) We calculate the emf

f is prop to m1xm2 double m1 double force

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.