[RosSin]

I'm having a little trouble with these q's
Q1. Constructive interference occurs at a given point when:

A. The path difference between waves arriving from 2 sources at the point is equal to an integral number of wavelengths
B. Waves from 2 sources arrive at the point with the same phase
C. all of the other answers
D. The shape of the waves from 2 sources look the same at the point
E. Waves from 2 sources travel the same distance to reach the point

Q2. A saxophonist is playing in a small room. When she plays a sustained musical note (A - wavelength 0.375 m), there are clear diffraction minima outside the door. If the first minimum is at 35 degrees, what is the width of the door?

A. 0.4 m
B. 0.6 m
C. 0.65 m
D. 0.35 m
E. 0.45 m

Thanks

[Perito]

Q1. Constructive interference occurs when two waveforms are "in phase". This occurs from answers A,B,D, and E. Therefore answer C (all of the other answers) is the correct choice.

Q2. I think this is simply "single-slit diffraction". You can Google that if you wish. The formula that controls single-slit diffraction is



where m is 1,2,3, etc.
λ is the wavelength of the wave
W is the width of the slit.

The equation gives the angles of diffraction maxima, and not minima. So we have to think here.

Given that λ is 0.375 Meters, there will be diffraction maxima at



I think the first minimum would come half way before that. (This is the assumption that is probably wrong and is probably the reason for the error).











But that isn't one of the choices, so I probably didn't do it correctly. Maybe this can help you figure out what do do?

[RosSin]

That's OK. Yeah, your working out will be helpful.

Just more questions...

q. In a Young's double-slit experiment, the slit separation is doubled. This will effect the fringe pattern by?
A decreasing the fringe intensity
B increasing the fringe intensity
C decreasing the fringe spread
D increasing the fringe spread

q. Destructive interference occurs at a given point when:
A Waves from 2 sources arrive at the point with the same phase
B The path difference between waves arriving from 2 coherent sources at the point is equal to half integral number of wavelengths
C Waves from 2 sources travel the same distance to reach the point
D The shape of the waves from 2 sources look the same at the point
E The path difference between waves arriving from 2 sources at the point is equal to an integral number of wavelengths

Thank-you

[RosSin]

Another question

q. What happens to the form of an interference pattern if the slits are moved farther apart?

A pattern spreads out
B pattern compresses

Thanks

[guan]

Slits move farther apart indicates that the pattern compresses.