Water Waves

Water Waves

Interference... A single source

Interference... Two sources

At the point where they meet they are out of step—one is on the right foot and the other on the left foot.

10 steps

y

d11 steps

If two people walk toward a point and both start on the same foot--

Constructive interference— a bright spot.

– If two beams of light meet and are both on the same foot then their intensities add.

Destructive interference— a dark spot.

– If two beams of light meet and are opposite feet then their intensities cancel and you get a dark spot.

DOING THE DISHES IS NOT A PROCESS, IT'S AN

OUTCOMESuccess equals failure plus a good story?

Luke 1418 And they all with one consent began to make excuse. The first said unto him, I have bought a piece of ground, and I must needs go and see it: I pray thee have me excused.…33 So likewise, whosoever he be of you that forsaketh not all that he hath, he cannot be my disciple.

What do we get

A. Constructive interference— a bright spot.

B. Destructive interference— a dark spot.

C. Somewhere in between.

What do we get

A. Constructive interference— a bright spot.

B. Destructive interference— a dark spot.

C. Somewhere in between.

What do we get

A. Constructive interference— a bright spot.

B. Destructive interference— a dark spot.

C. Somewhere in between.

Discussion question: For shorter steps (shorter wavelength) the minimums and maximums

A. Get closer together

B. Get further apartC. None of the above

Discussion question: When the slits get closer together the minimums and maximums . . .

A. Stay the sameB. Get closer

togetherC. Get further apartD. None of the above

How can I calculate where fringes will appear?

Discussion question: An interference pattern is formed on a screen by shining a planar wave on a double-slit arrangement (left). If we cover one slit with a glass plate (right), the phases of the two emerging waves will be different because the wavelength is shorter in glass than in air. If the phase difference is 180°, how is the interference pattern, shown left, altered?

A. The pattern vanishesB. The bright spots get

closer together.C. The bright spots get

farther apart.D. There are no changes.E. Bright and dark spots are

interchanged

Why don’t I see an interference pattern

From two light bulbs?

Coherence(temporal and spatial)

Polarization

Interference of BEC

Discussion question: Can you get a real image from a diverging lens

A. YesB. NoC. I don’t know

Group question: A 10 cm tall object is placed 8 cm to the left of a converging lens of focal length 4 cm. A diverging lens of focal length -6 cm is 6 cm to the right of the converging lens. The image is A. Real and upright

B. Real and invertedC. Virtual and uprightD. Virtual and inverted