PHYSICS WAVE MC 2條

Option A.
The crest of P occurs at one-fourth of a cycle (i.e. a phase of pi/2) earlier than Q.
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Option B

Wavelength = 8/2 m = 4 m
Hence, distance between two wave crests measured along the wall
= 4/sin(30) m = 8 m
Since distance between two crests ( 8 m) has a phase of 2.pi
thus phase between points 1 m apart = 2.pi/8 = pi/4