All materials on our website are shared by users. If you have any questions about copyright issues, please report us to resolve them. We are always happy to assist you.

Information Report

Category:
## Documents

Published:

Views: 3 | Pages: 19

Extension: PDF | Download: 0

Share

Related documents

Description

Announcements 11/12/10 Prayer Term project progress report due Saturday night Still missing slinkies from: a. Stephen Grant b. Chris Read c. Roger…

Transcript

Announcements 11/12/10 Prayer Term project progress report due Saturday night Still missing slinkies from: a. Stephen Grant b. Chris Read c. Roger Brown d. Tess Larson (She dropped the class; she’s just on the list here so I don’t forget about her) Two mathematical facts we will use: eix eix eix eix cos x sin x 2 2i Reading Quiz According to the book, a double-slit diffraction pattern (viewed on a screen far from the slits) looks like: a. A series of equal amplitude peaks, equally spaced b. A series of equal amplitude peaks, alternating between two spacing distances c. A series of alternating amplitude peaks, equally spaced d. A series of alternating amplitude peaks, alternating between two spacing distances Water Waves Credit: next several slides from Dr. Durfee Water Waves Interference... A single source Interference... Two sources Double slit experiment aka “Young’s Double Slit” Exactly the same as min the two speaker demo max min max Goal: what’s the shape of that curve? How can we predict where the maxima & minima will be? intensity screen here Experimental challenge How do you get two points sources of light that are oscillating in phase with each other? a. How did we do it with sound? b. Options for light? (I can only think of two) c. What he did: Image credit: Wikipedia How to solve the problem Complex numbers!! The light from each slit travels a different distance a. This creates a phase shift b. Incorporate the phase shift into eif First: what’s the phase shift for two waves oscillating in phase with a known DPL? f = ( DPL / l ) 360 f = 2pDPL / l What’s DPL? Clicker Vote: What should f = 2pDPL / l we measure the path length relative to? a. The top slit b. The bottom slit c. Halfway between the two slits Approximation #1: d is small enough that the two rays are parallel. Requires d L. The Answer Etot = Etop slit + Ebottom slit f = 2pDPL / l =… I ~ |E|2 I=… Plot of I(y) for I0=1, l=500 nm, L=1 m, d=1mm How did I turn q into y? Approximation #2: q is small enough that qy/L. Requires y L. Plots 2p d 2 I I 0 cos sin q l 2 2 p dy I I 0 cos q tan 1 y / L l L (approx. 1 only) (approx. 1 and 2) min max min max intensity screen here max min max min max min max screen here How to predict max/min 2 2p d 2 p dy I I 0 cos sin q I I 0 cos l 2 lL Max: cosx = 1 … d sinqbright ml Min: cosx = 0 … d sinqdark (m 12 )l What you need to know 2 2p d 2 p dy I I 0 cos sin q I I 0 cos l 2 lL How to solve the problem this way—works for any number/pattern of slits a. Three slits on HW 32-5 b. Potential problem like this on exam This only works for very narrow slits (width separation between slits) The two formulas above (on notecard, unless you can quickly derive them) Conditions for max/min (on notecard, unless you can quickly derive them) How Young did his experiment Wrapping Up 2p d2 2 p dy I I 0 cos sin q I I 0 cos l 2 lL d dy max : sin q m max : m l lL d 1 dy 1 min : sin q m min : m l 2 lL 2 The fast way to get these Demo: Double-slit experiment

Recommended

1 page

1 page

6 pages

28 pages

14 pages

Related Search

We Need Your Support

Thank you for visiting our website and your interest in our free products and services. We are nonprofit website to share and download documents. To the running of this website, we need your help to support us.

Thanks to everyone for your continued support.

No, Thanks

SAVE OUR EARTH

We need your sign to support Project to invent "SMART AND CONTROLLABLE REFLECTIVE BALLOONS" to cover the Sun and Save Our Earth.

More details...Sign Now!

We are very appreciated for your Prompt Action!

x