Single-Slit Diffraction and the Effect of Refractive Index on Central Peak Width

[fubag]

[SOLVED] Single-Slit Diffraction

Homework Statement

You have been asked to measure the width of a slit in a piece of paper. You mount the paper 80.0 centimeters from a screen and illuminate it from behind with laser light of wavelength 633 nanometers (in air). You mark two of the intensity minima as shown in the figure, and measure the distance between them to be 17.9 millimeters.

If the entire apparatus were submerged in water, would the width of the central peak change?

a.The width would increase.
b.The width would decrease.
c.The width would not change.

Homework Equations

asin(theta) = m(lambda)

The Attempt at a Solution

Well for the first part of this question I found the width of this slit in air to be 170 micrometers.

I know this is a conceptual question, but I need help understanding exactly what happens. I know the index of refraction changes from 1 to 1.33.

 

[alphysicist]

Hi fubag,

When the apparatus is underwater, what will change about the light?

 

[fubag]

lamda would change by a factor of decreasing 1.33 so the width would decrease therefore?

 

[Volcano]

how do you calculute "width of the central peak"? Put the new lambda there.

 

[fubag]

ok thanks a lot!