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**1. The problem**

A HeNe laser (wavelength = 633nm) is used to illuminate an opaque plate containing a a specified aperture. The light which passes through the aperture falls on a screen at a distance of 4 m from the aperture plate.

**c)**The aperture is replaced by two long rectangular slits, each of width 0.050mm and with their centers seperated by 0.150mm. Make a third sketch of intensity vs position again with a numerical scale.

**d)**With the same aperture from c, the laser light source is replaced by a normal electric filament light bulb plus a red filter. Explain what will now be seen on the screen and why it differs from the results with a laser,

## Homework Equations

**c)**I have drawn a wave like with a single slit diffraction, in an envelope with another wave. I used this equation y= m*lamda*D/d

where D = distance to screen and d = distance from centers of slits.

**d)**y= m*lamda*D/d

## The Attempt at a Solution

**c)**So for y i got 0.01688, so i'm not sure whether to use this as my numerical scale, and whether to draw two seperate waves or the wave envelope phenomena i'v seen in my textbook.

**d)**Due to y= m*lamda*D/d, y is proportional to lamda, so red being the highest wavelength , y will increase and the diffraction pattern will broaden.