Phys 104 - BlackBoard Notes: Diffraction and Interference - Spring [an error occurred while processing this directive]

Diffraction & Interference
BlackBoard Notes

Note: Next week ("Radioactivity of a Smoke Detector") - no eating or drinking during lab!

Three experiments (Order doesn't matter!):

Observe diffraction, interference patterns (single- and double-slit).
Measure λ of red line of hydrogen.
Measure extreme blue and red λ's of visible light.

Don't move the equipment
Watch the meter sticks on the floor in the back
Move your stuff out of the way so nobody trips

Diffraction, interference – a qualitative analysis:

Single Slit Single Slit:
How does a wider slit width
affect the diffraction pattern?

Double Slit Double Slit:
How does a greater separation between slits
affect the interferece pattern?

Reset the slit discs when finished!

Wavelength of red hydrogen light:

mλ = d sinθ
d = 32,700 nm

x/d

m lambda

Limits of vision:

Visible spectrum

mλ = d sinθ

d = 1900 nm
What is m?

Note: Can't use small angle approximation!!

Return to Setup

	Single Slit: How does a wider slit width affect the diffraction pattern?

	Double Slit: How does a greater separation between slits affect the interferece pattern?


©	St. Lawrence University	Department of Physics