## GR0877 Problem 42

**PROBLEM STATEMENT**: *This problem is still being typed*.

**SOLUTION**: (**E**) From the picture we see that the period of oscillations (this is phase difference) is approximately 6 cm, while the difference between two points of equal voltage-level (say, zero-level) for two waveforms is 2 cm. Thus, the phase difference between waveforms is .

*Found a typo? Comment!*

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How do you know it’s 120 and not 90?

So, there are 3 squares for every 90 degrees. If you look at the shift in Channel 2 to the right, you end up with ~4 squares difference, which implies 4/3*90=120. If you shift it to the left, you need to by ~2, so that 2/3*90 = 60.

Is there some reason why it couldn’t be 60?

Wrong. 180 degrees.

Well, did you read the solution (carefully)? I think it’s clear.