In Young's double slit experimental set up, if the wavelength alone is doubled, the band width B becomes

• $\frac{\mathrm{\beta }}{2}$

• 2β

• 3β

• β

Which one of the following statements is correct?

• Monochromatic light is never coherent

• Monochromatic light is always coherent

• Coherent light is always monochromatic

• Coherent light is sometimes monochromatic

In a Young's double slit experiment, the intensity at a point where the path difference is $\frac{\mathrm{\lambda }}{6}$(λ = wavelength of the light) is I. If I₀ denotes the maximum intensity, then $\frac{\mathrm{I}}{{\mathrm{I}}_0}$ is equal to

• $\frac{1}{2}$

• $\frac{\sqrt{3}}{2}$

• $\frac{1}{\sqrt{2}}$

• $\frac{3}{4}$

A narrow slit of width 2 mm is illuminated by monochromatic light of wavelength 500 nm. The distance between the first minima on either side on a screen at a distance of 1 m is

• 5 mm

• 0.5 mm

• 1 mm

• 10 mm

35.

The principle of superposition is basic to the phenomenon of

• total internal reflection

• interference

• reflection

• refraction

Light of wavelength 6000 $\stackrel{\circ }{\mathrm{A}}$ falls on a single slit of width 0.1 mm. The second minimum will be formed for the angle of diffraction of

• 0.08 rad

• 0.06 rad

• 0.012 rad

• 0.15 rad

In a double slit experiment, the screen is placed at a distance of 1.25 m from the slits. When the apparatus is immersed in water (µ_w = 4/3), the angular width of a fringe is found to be 0.2°. When the experiment is performed in air with same set up, the angular width of the fringe is

• 0.4°

• 0.27°

• 0.35°

• 0.15°

In Young's experiment, the third bright band for light of wavelength 6000 $\stackrel{\circ }{\mathrm{A}}$ coincides with the fourth bright band for another source of light in the same arrangement. Then the wavelength of second source is

• $3600 \stackrel{\circ }{\mathrm{A}}$

• $4000 \stackrel{\circ }{\mathrm{A}}$

• $5000 \stackrel{\circ }{\mathrm{A}}$

• $4500 \stackrel{\circ }{\mathrm{A}}$

A slit of width a is illuminated by red light of wavelength 6500 $\stackrel{\circ }{\mathrm{A}}$. If the first minimum falls at θ = 30°, the value of a is

• 6.5 × 10^-4 mm

• 1.3 micron

• 3250 $\stackrel{\circ }{\mathrm{A}}$

• 2.6 × 10^-4 cm

Two beams of light of intensity I₁ and I₂ interfere to give an interference pattern. If the ratio of maximum intensity to that of minimum intensity is $\frac{25}{9}$, then $\frac{{\mathrm{I}}_1}{{\mathrm{I}}_2}$ is

• $\frac{5}{3}$

• 4

• $\frac{81}{625}$

• 16