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Physics · 2022 · 3 marks
CBSE 2022 · Region 3 · Set 1 · Q10
In a Young's double slit experiment using light of wavelength 600 nm, the slit separation is 0.8 mm and the screen is kept 1.6 m from the plane of…
In a Young's double slit experiment using light of wavelength $\displaystyle 600$ nm , the slit separation is $\displaystyle 0.8$ mm and the screen is kept $\displaystyle 1.6$ m from the plane of the slits. Calculate :
(i)
the fringe width
(ii)
the distance of (a) third minimum and (b) fifth maximum, from the central maximum.
Marking-scheme solution
(i)
Calculating Fringe width
(ii)
Calculating distances of fringes
(i)
$\displaystyle \beta=\frac{\lambda D}{d}=\frac{600 \times 10^{-9} \times 1.2}{8 \times 10^{-4}}=1.2 \mathrm{~mm}$
(ii)(a)
$\displaystyle x_{3}=\frac{5}{2} \frac{\lambda D}{d}=\frac{5}{2} \times 1.2 \mathrm{~mm}=3 \mathrm{~mm}$
(iii)(b)
$\displaystyle x_{5}=\frac{5 \lambda D}{d}=2 \times 3 \mathrm{~mm}=6 \mathrm{~mm}$
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