It is called absorption spectrum because a gas of hydrogen will make a line spectrum and if viewed for another angle it would be between a continuum light and a emission line spectrum
Answer:
The contribution of the wavelets lying on the back of the wave front is zero because of something known as the Obliquity Factor. It is assumed that the amplitude of the secondary wavelets is not independent of the direction of propagation, Sources: byju's.com
The answer to this would inFact be A
About 10% to 15% of system charge