David Sang and Graham Jones Solutions for Chapter: Superposition of Waves, Exercise 8: Questions

Use the equation $\lambda =\frac{ax}{D}$ to explain the following observations:

(a) With the slits closer together, the fringes are further apart.

Use the equation $\lambda =\frac{ax}{D}$ to explain the following observations:

(b) Interference fringes for blue light are closer together than for red light.

Use the equation $\lambda =\frac{ax}{D}$ to explain the following observations:

(c) In an experiment to measure the wavelength of light, it is desirable to have the screen as far from the slits as possible.

Yellow light from a sodium source is used in the double-slit experiment. This yellow light has wavelength $589 \mathrm{nm}$. The slit separation is $0.20 \mathrm{mm}$, and the screen is placed $1.20 \mathrm{m}$ from the slits. Calculate the separation between adjacent bright fringes formed on the screen.

In a double-slit experiment, filters were placed in front of a white light source to investigate the effect of changing the wavelength of the light. At first, a red filter was used instead $(\lambda =600 \mathrm{nm})$ and the fringe separation was found to be $2.4 \mathrm{mm}$. A blue filter was then used instead $(\lambda =450 \mathrm{nm})$. Calculate the fringe separation with the blue filter.