## Question

In a two-slit experiment with monochromatic light, fringes are obtained on a screen placed at some distance from the slits. If the screen is moved by towards the slits, the change in fringe-width is . If the distance between the slits is 10^{–3 }

M, calculate the wavelength of the light used.

### Solution

Initially, the fringe-width is given by

Where *D* is the distance of the screen and *d* is the distance between the two sources (slits). On moving the screen through distance *x* towards the slits, the new fringe-width is

#### SIMILAR QUESTIONS

The absolute refractive index of air is 1.0003 and the wavelength of yellow light in vacuum is 6000 Ã…. Find the thickness of air column which will have one more wavelength of the yellow light than in the same thickness of vacuum.

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^{ –31}kg,

*m*= 1.67 × 10

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*h*= 6.63 × 10

^{ –34}Js).

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In Young’s experiment on interference of light a fringe of width 0.04 cm is obtained on a screen placed at a distance of 50 cm from the slits when the wavelength of the light used is 5000 Ã…. If the distance of the screen from the slits remains unchanged, what will be the width of the fringe if light of wavelength 4000 Ã… is used?

The fringe-width is obtained as 0.060 cm on using light of wavelength 5000Ã… in Young’s experiment. What value of wavelength of light should be taken so that the width of the fringe on the screen could be obtained as 0.040 m, if the distance of screen from the slit is halved?

In Young’s experiment the interval between the slits is 0.200 mm. For the light of wavelength 600 mμ, interference fringes are formed on a screen at a distance of 80.0 cm. (i) What is the distance of the second dark fringe from the central fringe? (ii) What is the distance of the second bright fringe from the central fringe?