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Other Applications of Two-Point Source Interference. Path Difference. Path Difference the difference in distance travelled by the two waves from their respective sources to a given point on the pattern. Abbreviated PD. PD = m λ. Consider the following scenario:.
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Path Difference • Path Difference the difference in distance travelled by the two waves from their respective sources to a given point on the pattern. • Abbreviated PD
Waves are taking 2 paths to antenna: direct and reflected paths. • Reflected path is longer than the direct path. • They travel 2d further. • This is the destructive path…
Using the wave equation (v = fλ), we can calculate the wavelength of the signal. • Remember: EM waves travel at 3 x 108 m/s • Then, plugging into 2d = mλ (just plug 0.5 into m), we can solve for one distance from the house to the cliff that will cause destructive interference. • Other distances that cause destructive int. can be found subbing in 1.5, 2.5, 3.5, etc…
Same principle can be applied to interference from planes flying overhead. • By subbing in different values for m, the different potential heights can be found.
These ideas are taken into account when designing, say, an auditorium. You don’t want areas of destructive interference in the sound waves. • Engineers take this into account.