Question

A 17-mm-wide diffraction grating has rulings of 530 lines per millimeter. White light is incident normally on the grating. What is the longest wavelength that forms an intensity maximum in the fifth order

Answer 1

377 nm

Step-by-step explanation:

Number of lines per meter is,
`N &=530 * 1000 \\ &=530000 \text { lines } / \mathrm{m} \end{aligned}`

Grating element is,
`d=(1)/(N)`

`\lambda &=(1.8868 * 10^(-6))/(5(\sin 90)) \\ &=0.377 * 10^(-6) \mathrm{~m} \\ &=377 \mathrm{~nm}`