Visible light passes through a diffraction grating that has 900 slits per centimeter, and the interference pattern is observed on a screen that is 2.24 m from the grating. In the first-order spectrum, maxima for two different wavelengths are separated on the screen by 3.20 mm . What is the difference between these wavelengths? Answer in meters.

Respuesta :

Answer:

The difference between these wavelengths is 15.85 nm.

Explanation:

Given that,

The number of lines on the grating N= 900 cm

Distance between screen grating L= 2.24 m

Order number = 1

Distance y = 3.20 mm

We need to calculate the width of the slit

Using formula of width

[tex]d=\dfrac{1}{N}[/tex]

Put the value into the formula

[tex]d=\dfrac{1}{900}[/tex]

[tex]d =0.00111 = 1.11\times10^{-5}\ m[/tex]

We need to calculate the angular distance

[tex]\theta=\dfrac{\lambda}{d}[/tex]

The angular separation for different wavelength  is

[tex]\Delta \theta=\dfrac{\lambda_{1}-\lambda_{2}}{d}[/tex]

We know that,

Linear separation is

[tex]\Delta y = \Delta \theta L[/tex]

We nee to calculate the difference between these wavelengths

Put the value into the formula of angular separation

[tex]\Delta y=L(\dfrac{\lambda_{1}-\lambda_{2}}{d})[/tex]

[tex]\lambda_{1}-\lambda_{2}=\dfrac{\Delta y\times d}{L}[/tex]

[tex]\lambda_{1}-\lambda_{2}=\dfrac{3.20\times10^{-3}\times1.11\times10^{-5}}{2.24}[/tex]

[tex]\lambda_{1}-\lambda_{2}=1.585\times10^{-8}[/tex]

[tex]\lambda_{1}-\lambda_{2}=15.85\ nm[/tex]

Hence, The difference between these wavelengths is 15.85 nm.