AS physics help

So I stumbled upon this multiple choice question on my summer transition work: "A wave of frequency 5 Hz travels at 8 km s–1 through a medium. What is the phase difference, in radians, between two points 2 km apart?"

So first I calculated the wavelength by working out 8000 x 5 to get 1600m. I then worked out 360 x 2000/1600 to get the final answer of 450 degrees. However, my answer doesn't show up on the choice list so I'm assuming it's wrong? If that's the case can someone tell me what I've done wrong?

B U M P

450 degrees is correct, but waves ‘repeat’ every 360 degrees. So 450 degrees is equivalent to 450 - 360 = 90 degrees, which is how it would usually be shown.

Reply 3

hoixw

The phase difference is defined as a function between 0 and 2pi. This is because waves complete one oscillation every 360 degrees, so they repeat. If you get a result above 360 degrees (or 2pi), just minus 2pi from the answer.

Reply 4

Soul Wavel3ngth

Original post by nzy

450 degrees is correct, but waves ‘repeat’ every 360 degrees. So 450 degrees is equivalent to 450 - 360 = 90 degrees, which is how it would usually be shown.