Two slits are made 0.1 mm apart and the screen is placed 2 m away. The fringe separation when a light of wavelength 500 nm is used is ____________.
Fill in the blank with the correct answer from the options given below.
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 1 cm
In Young's double-slit experiment the fringe separation is
\( \displaystyle \beta = \frac{\lambda D}{d} \)
\( \lambda = 500\,\mathrm{nm} = 5\times10^{-7}\,\mathrm{m} \)
\( D = 2\,\mathrm{m} \)
\( d = 0.1\,\mathrm{mm} = 1\times10^{-4}\,\mathrm{m} \)
\( \displaystyle \beta = \frac{5\times10^{-7} \times 2}{1\times10^{-4}} = 1\times10^{-2}\,\mathrm{m} = 1\,\mathrm{cm} \)
Note: NTA picked this question from an NCERT Exemplar problem and changed the figures. Do not ignore the Exemplar while practising numericals.
NCERT Exemplar:
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