Question

In a plane transmission grating, the width of a ruling is $12000\stackrel{o}{A}$ and the width of a slit is $8000\stackrel{o}{A}$ , the grating element is:
A. 20 $\mu m$
B. 2 $\mu m$
C. 200 $\mu m$
D. 10$\mu m$

Answer 1

Hint: The width of ruling is already given in the question. The width of the slit is also given in the question. The grating element is generally considered as the sum of width of the ruling and of the slit.

Complete step by step solution:
We know that,
Grating element is the sum of the width of the ruling and the width of the slit.
Therefore,
Grating element =12000$\stackrel{\circ }{A}$+8000$\stackrel{\circ }{A}$
That when solved is equals to,
20000$\stackrel{\circ }{A}$
Now,
we know that 1μm=10000$\stackrel{\circ }{A}$
Therefore 20000$\stackrel{\circ }{A}$ = 2μm

So, the correct answer is “Option B”.

Additional Information:
An arrangement consisting of an outsized number of parallel slits of same width and separated by equal spaces is called grating. It can be said that the distance between two consecutive slits can be called the grating element.
Diffraction is the process exhibited by wave fronts in which a beam of light or any other system of waves like light waves is spread out as a result of passing through a short aperture or across an edge, or through a slit, typically accompanied by the interference between the wave forms. The spread out is in such a way that there is alternative interference, that is, constructive and destructive.

Note: Generally mistakes can occur in copying the values of the ruling and of the slit, it is just the sum of both the values of the width. Always convert the value of the grating element from angstrom to micrometer.