Your name: _____________________

Print this page, record your answers on it, and show it to your lab TF at the start of your lab session.

In this experiment you will use a laser and a set of narrow slits to investigate interference and diffraction. Waves exhibit interference and/or diffraction when they encounter openings and/or obstacles that are comparable in size to the wavelength.

The simulation above should help you answer the following questions.
At the bottom of the simulation you will see a magnified view of the single or double slit. Above that, there are two different representations of the pattern of light and dark fringes made by the light on a screen after passing through the slit(s).

Start with the single slit.

(a) If the width of the single slit is increased, what happens to the width of the bright central region on the screen? That width ...

Now, switch to the "double slit", after viewing the "double source" pattern. A laser is shone through a double slit, two narrow openings placed close together. An interference pattern of bright and dark fringes is observed on a screen some distance from the double slit.

(b) If the separation between the openings in the double slit is increased, what happens to the distance between the fringes on the screen? That distance ...

(c) If the distance between the double slit and the screen is increased, what happens to the distance between the fringes on the screen? That distance ...

(d) If the wavelength of the laser light is increased, what happens to the distance between the fringes on the screen? That distance ...

(e) If the entire apparatus is immersed in water, what would happen to the distance between the fringes on the screen? That distance ...

Briefly justify your answer to part (e) above.