QATS Trial 2019 (1 Viewer)

[krypticlemonjuice]

Can someone please explain how we do questions like this?

 

[wizzkids]

Obviously the wave fronts are separated the wavelength λ.
Place numbers on the wave fronts radiating out from each source.
Maximum constructive interference occurs where wave crests coincide.
There are going to be multiple points where the wave fronts are out-of-phase by exactly 2λ.
The points that satisfy these condition should radiate out along four lines, because these are circular waves spreading radially.
With these hints, can you now solve the problem?

 

[krypticlemonjuice]

Obviously the wave fronts are separated the wavelength λ.
Place numbers on the wave fronts radiating out from each source.
Maximum constructive interference occurs where wave crests coincide.
There are going to be multiple points where the wave fronts are out-of-phase by exactly 2λ.
The points that satisfy these condition should radiate out along four lines, because these are circular waves spreading radially.
With these hints, can you now solve the problem?

I kinda get what you mean, but i still don't really understand how to interpret the diagram. How would i know where they are out of phase by 2λ?

 

[wizzkids]

First, we must assume that the wave fronts are drawn as if they are synchronous, that is they are generated at the same times. Next we look for places where the first wavefront from the left-hand source intersects with the third wavefront from the right-hand source, and draw a point. This is a point where the waves fronts are out-of-phase by exactly 2λ. There are sixteen points that satisfy these conditions, as shown below. There are no more points after the fifth wavefront because we don't have the seventh and subsequent wavefronts in the diagram.

 

[krypticlemonjuice]

First, we must assume that the wave fronts are drawn as if they are synchronous, that is they are generated at the same times. Next we look for places where the first wavefront from the left-hand source intersects with the third wavefront from the right-hand source, and draw a point. This is a point where the waves fronts are out-of-phase by exactly 2λ. There are eight points that satisfy these conditions, as shown below. There are no more points after the fifth wavefront because we don't have the seventh and subsequent wavefronts in the diagram.
View attachment 40107

Ohhhh ok, that makes so much sense, thank you so much for your help!