Question

What is used to measure Doppler line broadening?
A. Polaroid
B. Diffraction grating
C. Herapathite
D. Plasma

Answer 1

Hint: Firstly defining the Doppler line broadening with Doppler Effect. Then, compare all the options and study about Doppler’s effect. The plasma uses for measuring thermal motion of particles we also have to know that others terms have any relation with Doppler line broadening

Complete step-by-step solution:
Doppler line broadening can be defined as
It is the phenomenon of expanding spectral lines due to the Doppler Effect. This is caused by distribution of molecules. Different velocities of particles result in Doppler shifts that accumulate the effect of line broadening.
Doppler Effect is the change in frequency of wave when an object is in motion exhibiting the sound frequency higher in front than on back. For ex: an ambulance front will most likely have a higher sound of siren in comparison to the back of it.
 Taking the option A. Polaroid
In Polaroid, a large sheet of synthetic material packed with diachronic substance is parallel to another and it transmits light in only one direction. It deals with the reduction of light waves through its surface. Thus, it can’t measure the Doppler line broadening.
Taking the option B. Diffraction grating
In diffraction grating, it’s an optical element that disperses light composed of lots of different wavelengths into light parts by wavelength. It is used to distinguish the wavelength consisting of which components of wavelengths. Thus, it can’t measure the Doppler line broadening.
Taking the option C. herapathite
It’s a chemical compound of diachronic crystals; it can be used for polarizing light, Also known as iodoquinine sulfate. It's the same as the above polarization. Thus, it can’t be used for measuring the Doppler line broadening.
Taking the option C. Plasma
In plasma, the thermal Doppler broadening is one reason because in some cases the thermal Doppler broadens due to the thermal motion of molecules. Then, the expansion can be dependent upon frequency of spectral line, mass and their temperature.
Thus the final result is option C. Plasma
Note:Doppler broadening, the physical phenomenon driving the Fuel temperature coefficient of reactivity, has also been used as a design consideration in high-temperature nuclear reactors. Doppler broadening can also be used to determine the velocity distribution of a gas given its absorption spectrum. Natural broadening is always present, is the same at all wavelengths, and is very small.