
Yellow light from a sodium source is used in the double-slit experiment. This yellow light has wavelength . The slit separation is , and the screen is placed from the slits. Calculate the separation between adjacent bright fringes formed on the screen.

Important Questions on Superposition of Waves


Monochromatic light is incident normally on a diffraction grating having lines per centimetre. The angular separation of the zeroth- and first-order maxima is found to be . If , calculate the angle for the second-order maximum.

Monochromatic light is incident normally on a diffraction grating having lines per centimetre. The angular separation of the zeroth- and first-order maxima is found to be . If , calculate the angle for the second-order maximum.
(b) Repeat the calculation of for , and so on. Determine how many maxima can be seen. Explain your answer.

Consider the equation . State and explain how the interference pattern would change when:
(a) The wavelength of the incident light is increased for the same grating

Consider the equation . State and explain how the interference pattern would change when:
(b) The grating is changed for one with more lines per for the same incident light.

A student is trying to make an accurate measurement of the wavelength of green light from a mercury lamp. The wavelength $\lambda$ of this light is . Using a double-slit of separation , the student can see clear bright fringes on a screen at a distance of from the slits. The student can measure their overall width to within
Using a ruler. The student then tries an alternative experiment using a diffraction grating with lines . The angle between the two second-order maxima can be measured to within .
(a) Determine the width of the fringes that the student can measure in the first experiment.

A student is trying to make an accurate measurement of the wavelength of green light from a mercury lamp. The wavelength $\lambda$ of this light is . Using a double-slit of separation , the student can see clear bright fringes on a screen at a distance of from the slits. The student can measure their overall width to within
Using a ruler. The student then tries an alternative experiment using a diffraction grating with lines . The angle between the two second-order maxima can be measured to within .
(b) Determine the angle of the second-order maximum that the student can measure in the second experiment.
