Question 153: Waves Optics

Question

In a Young’s double slit experiment with slit separation 0.1 mm, one observes a bright fringe at angle  $${1 \over {40}}$$ by  using light of wavelength $$\lambda $$1.  When the light of wavelength $$\lambda $$2 is used a bright fringe is seen at the same angle in the same set up. Given that $$\lambda $$1 and $$\lambda $$2 are in visible range (380 nm to 740 nm), their values are -

Accepted Answer

Path difference = d sin$$	heta $$ $$ \approx $$ d$$	heta $$
= 0.1 $$ 	imes $$ $${1 \over {40}}$$ mm = 2500nm
or   bright fringe, path difference must be integral multiple of $$\lambda $$.
$$ 	herefore $$   2500 = n$$\lambda $$
1
= m$$\lambda $$
2
$$ 	herefore $$   $$\lambda $$
1
= 625 (from n = 4),  $$\lambda $$
2
= 500 (from m = 5)

Answer

400 nm, 500 nm

Answer

625 nm, 500 nm

Answer

380 nm, 500 nm

Answer

380 nm, 525 nm

Waves Optics

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