1
WB JEE 2024
MCQ (Single Correct Answer)
+1
-0.25

Light of wavelength $$6000 \mathop A\limits^o$$ is incident on a thin glass plate of r.i. 1.5 such that the angle of refraction into the plate is $$60^{\circ}$$. Calculate the smallest thickness of the plate which will make dark fringe by reflected beam interference.

A
$$1.5 \times 10^{-7} \mathrm{~m}$$
B
$$2 \times 10^{-7} \mathrm{~m}$$
C
$$3.5 \times 10^{-7} \mathrm{~m}$$
D
$$4 \times 10^{-7} \mathrm{~m}$$
2
WB JEE 2024
MCQ (Single Correct Answer)
+1
-0.25

In a single-slit diffraction experiment, the slit is illuminated by light of two wavelengths $$\lambda_1$$ and $$\lambda_2$$. It is observed that the $$2^{\text {nd }}$$ order diffraction minimum for $$\lambda_1$$ coincides with the $$3^{\text {rd }}$$ diffraction minimum for $$\lambda_2$$. Then

A
$$\frac{\lambda_1}{\lambda_2}=\frac{2}{3}$$
B
$$\frac{\lambda_1}{\lambda_2}=\frac{5}{7}$$
C
$$\frac{\lambda_1}{\lambda_2}=\frac{3}{2}$$
D
$$\frac{\lambda_1}{\lambda_2}=\frac{7}{5}$$
3
WB JEE 2023
MCQ (Single Correct Answer)
+1
-0.25

A ray of monochromatic light is incident on the plane surface of separation between two media $$\mathrm{X}$$ and $$\mathrm{Y}$$ with angle of incidence '$$\mathrm{i}$$' in medium $\mathrm{X}$ and angle of refraction 'r' in medium Y. The given graph shows the relation between $$\sin \mathrm{i}$$ and $$\sin \mathrm{r}$$. If $$\mathrm{V}_{X}$$ and $$\mathrm{V}_{Y}$$ are the velocities of the ray in media X and Y respectively, then which of the following is true?

A
$$\mathrm{V}_{X}=\frac{1}{\sqrt{3}} \mathrm{~V}_{\mathrm{Y}}$$
B
$$\mathrm{V}_{\mathrm{X}}=\sqrt{3} \mathrm{~V}_{\mathrm{Y}}$$
C
Total internal reflection can happen when the light is incident in medium X.
D
$$v_{X}=\sqrt{3} v_{Y}$$, where $$v_{X}$$ and $$v_{Y}$$ are frequencies of the light in medium X and Y respectively.
4
WB JEE 2023
MCQ (Single Correct Answer)
+1
-0.25

X-rays of wavelength $$\lambda$$ gets reflected from parallel planes of atoms in a crystal with spacing d between two planes as shown in the figure. If the two reflected beams interfere constructively, then the condition for maxima will be, (n is the order of interference fringe)

A
$$\mathrm{d\tan\theta=n\lambda}$$
B
$$\mathrm{d\sin\theta=n\lambda}$$
C
$$\mathrm{2d\cos\theta=n\lambda}$$
D
$$\mathrm{2d\sin\theta=n\lambda}$$
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