Question

In solar system fraunhofer lines are present because
(A) Definite absorption takes place in photosphere of sun
(B) Definite absorption takes place in chromosphere of sun
(C) These wavelengths are not at all emitted by the sun
(D) Nuclear reaction takes place in the sun

Answer 1

Hint:
When you let sunlight pass through a prism, you can see that the light is broken up into the colors of the rainbow (a spectrum). If you observe the spectrum more carefully, you will find countless dark features. These are absorption lines caused by impurities.

Complete step by step solution
The spectrum of the sun’s solar radiation is close to that of a black body. The sun also emits X-rays, ultraviolet, visible light, infrared, and even radio waves. The energy in solar irradiation comes in the form of electromagnetic waves of a wide spectrum. Longer wavelengths have less energy than shorter ones such as visible light or UV. The sun is mostly made of hydrogen with smaller amounts of helium in the form of plasma. The main part of the sun has three layers: the core, the radiative zone, and the convection zone.
FRAUNHOFER LINES: are typical spectral absorption lines. Absorption lines are dark lines, narrow regions of decreased intensity, That are the result of photons being absorbed AS light passes from the source to the detector. In the sun, fraunhofer lines are a result of gas in the photosphere, the outer region of the sun. The photosphere gas has lower temperatures than the gas in the inner regions, and absorbs a little of the light emitted from those regions.
So, that option (A) is correct.

Note
Some fraunhofer lines were known to originate in absorption in the earth’s atmosphere. The depth of the absorption lines provide information about temperature, and the wavelength shifts of the lines tell us the motion of the gas.