Question

Monochromatic light passes through a double slit, producing interference, the distance between the slit centres is 1.2 mm and the distance between constructive fringes on a screen 5 m away is 0.3 cm. What is the wavelength?

Answer 1

The wavelength of the light is
`7200\ \AA`.

Step-by-step explanation:

Given that,

Distance between the slit centers d= 1.2 mm

Distance between constructive fringes
`\beta= 0.3\ cm`

Distance between fringe and screen D= 5 m

We need to calculate the wavelength

Using formula of width

`\beta=(D\lambda)/(d)`

Put the value into the formula

`0.3*10^(-2)=(5*\lambda)/(1.2*10^(-3))`

`\lambda=(0.3*10^(-2)*1.2*10^(-3))/(5)`

`\lambda=7.2*10^(-7)\ m`

`\lambda=7200\ \AA`

Hence, The wavelength of the light is
`7200\ \AA`.