What is grating?
A plane transmission diffraction grating is an arrangement consisting of large number of close, parallel, straight, transparent equidistant slits, each of equal width ‘a’, with neighbouring slit being separated by an opaque region of width ‘b’.
What is grating element?
The spacing (a+b) between the adjacent slits is called diffraction element or grating element or grating constant.
What is diffraction?
Bending of light at an obstacle or an aperture with size equivalent to the range of wavelength of light is called diffraction of light.
What are the two types of diffraction of light?
The diffraction phenomenon is divided into two types:
Fresnel diffraction and Fraunhofer diffraction.
- In the first type, either source or screen or both are at finite distance from the diffracting device.
- In the second type, both source and screen are effectively at infinite distance from the diffracting device. Fraunhofer diffraction is a particular limiting case of Fresnel diffraction.
What is resolving power of an instrument?
The resolving power of an optical instrument is its ability to resolve or separate the images of two nearby point objects so that they can be distinctly seen. It is equal to the reciprocal of the limit of resolution of the optical instrument.
What is the name of the eyepiece used?
Ramsden’s eyepiece
Why third order spectrum cannot be seen through telescope?
Since the maximum value of sin θ be one, θ can be 90°, therefore after calculation the maximum value of n is 2.874 which is less than three.
What is the main difference between the spectrum obtained by grating and that due to prism?
In grating spectrum, red colour is deviated (or diffracted) most and violet least. The sequence of the colours in grating spectrum is reverse than that of prism spectrum (VIBGYOR).
Which gives more intense spectrum-a prism or grating and why?
A prism gives more intense spectrum because it gives only one spectrum in which the entire light is concentrated, while in case of grating, the incident light is distributed into the diffraction spectra of various orders on both sides of the direct image.