PHYSICS LIGHT WAVES

2011-11-27 7:01 pm

Yellow light of wavelength 590nm is incident normally on a double-slit (slit separation is 0.15mm)

sketch the amplitude of the wave on the screen versus sin θ, where θ is the angle measured from the incident direction

the answer is Magnitudes of the peaks decrease as θ
increases

why when sin θ increases, the amplitude decreases???

why?? i don't understand

please help! thank you

回答 (1)

天同

2011-11-27 9:43 pm

✔ 最佳答案

The equation describing the wave amplitude with angle (theta) can be found in the following web-page:

In the equation, a is the slit width and d is the slit separation

http://vnatsci.ltu.edu/s_schneider/physlets/main/doubleslitintensity.shtml

You can see that the intensity of the peaks (which is the square of amplitude peaks) varies with angle (theta) is given by,

I = I(max).[sin(p)/p}^2
where p = pi.a.sin(theta)/入, where 入 is the wavelength
and I(max) is the intensity of the central peak

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