In: Physics
Problem 2. In diffraction experiments involving multiple wavelengths of light passing through the same aperture, the higher order maxima of one wavelength can coincide with a lower order maxima of a longer wavelength. In the above diffraction experiment, the 3rd maxima of 600 nm light is found to coincide with the 4th maxima of a different wavelength of light. What is the other wavelength?
Given m3 = 3, 3 = 600nm and m4 = 4, 4 = ?
We know that for a grating having grating element ( a + b ) the angle of diffraction in the mth order spectrum for a light of wavelength is given by
( a + b ) sin() = m
for a given grating ( a + b ) is constant i.e., same aperture and hence will be the same when m is constant.
m = constant
=> m33 = m44
=> 3 x 600nm = 4 x 4
=> 4 = 450nm
the other wavelength is 450nm