Question

The collimator in a spectrometer is used
A. To make measurement of deviation
B. To see the spectrum
C. To get parallel beam of light
D. Collimator is not a part of spectrometer

Answer 1

Hint: In optics, when we analyse light, then firstly we pass it through the collimator. Collimator consists of a tube and a slit of adjustable width at one end, and a convex lens at the other end.

Complete step by step answer:
A spectrometer consists of three basic components: a collimator, a refracting/diffracting element, and a telescope.
The light to be analysed, enters the collimator through a narrow slit which is placed at the focal point of the collimator lens.

The light leaving the collimator is therefore a thin, parallel beam, which ensures that all the light from the slit strikes the diffracting element at the same angle of incidence.
This is necessary if we want to form the sharp image.

Hence, the correct option is C, i.e., To get parallel beam of light

Additional Information:
A spectrometer is a simple scientific instrument. It bends a beam of light with a prism or diffraction grating. If the beam is composed of more than one colour of light, a spectrum is formed.Now we know that the various colours are refracted or diffracted to different angles. So, carefully measure the angle to which each colour of light is bent. The result gives us the unique information about the substance from which the light emanates.

Note: Students should understand the construction and working of a spectrometer. Students should keep in mind that before analysing light, we need to pass it through the collimator so that it forms the sharp image.