Aseries circuit contains an electric generator, three devices operated by electricity, and the necessary connecting wires. the resistances of the three devices are 20 ohms, 8 ohms, and 4 ohms. the resistance of the connecting wires can be neglected. what is the total resistance in the circuit?

Total resistance = 32 ohms

The total resistance of a series circuit is equal to the sum of individual resistances.

That is;

Rt = R1 + R2 + R3 + R4 + Rn

Where, Rt is the total resistance of the circuit, while R1 , R2, R3 and R4 are the resistance of the components in the circuit and so fourth.

Thus;

Rt = 20Ω + 8Ω + 4Ω

   = 32 Ohms

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.