A wave based explanation for double slit diffraction patterns

You will need:

• A compass, with the centre screw firmly tightened

• A sharp pencil

• A sheet of A4 graph paper

• A 30cm ruler.

A wave based explanation for double slit diffraction patterns

• Place your graph paper on the desk (landscape orientation).

• Make small pencil marks on the long edge along the bottom of the paper, at 12cm and 16cm.

• Set your compass to a radius of 1cm. Draw a semicircle, centred on the mark at 12cm.

• Draw a second semicircle, centred on the mark at 16cm.

• Repeat this process, with the compass radius set at 2cm, 3cm, 4cm, 5cm, 6cm and 7cm.

A wave based explanation for double slit diffraction patterns

• Draw a small dot, preferably in red ballpoint pen, in each place a wave crest meets another wave crest.

A wave based explanation for double slit diffraction patterns

….Like this….!

A wave based explanation for double slit diffraction patterns

• The dots should line up to show where we are getting constructive interference. Join the points with lines to show where the bright fringes will occur.