Wave Optics - Result Question 22

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22. In Young’s double slit experiment, the fringe width is found to be $0.4 mm$. If the whole apparatus is immersed in water of refrative index $\frac{4}{3}$, without disturbing the geometrical arrangement, the new fringe width will be [1990]

======= ####22. In Young’s double slit experiment, the fringe width is found to be $0.4 mm$. If the whole apparatus is immersed in water of refrative index $\frac{4}{3}$, without disturbing the geometrical arrangement, the new fringe width will be [1990]

3e0f7ab6f6a50373c3f2dbda6ca2533482a77bed:content/english/neet-pyq-chapterwise/physics/wave-optics/wave-optics—result-question-22.md (a) $0.30 mm$

(b) $0.40 mm$

(c) $0.53 mm$

(d) 450 microns

Topic 3: Diffraction, Polarization of Light &

Resolving Power23. The Brewsters angle $i_b$ for an interface should be

[2020]

(a) $30^{\circ}<i_b<45^{\circ}$

(c) $i_b=90^{\circ}$

(b) $45^{\circ}<i_b<90^{\circ}$

(d) $0^{\circ}<i_b<30^{\circ}$

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Answer:

Correct Answer: 22. (a)

Solution:

(a) $\beta^{\prime}=\frac{\beta}{\mu}=\frac{0.4}{\frac{4}{3}}=0.3 mm$

If the whole YDSE set up is taken in another medium then $\lambda$ changes. So $B$ changes.

In water $\lambda \omega=\frac{\lambda_a}{\mu_w}$

$ \Rightarrow \quad \beta \omega=\frac{B_a}{\mu_w}=\frac{3}{4} B_a $