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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 $2\pi$ 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 $2 \cdot 2 \pi/6 = 2\pi/3$.

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1. 08.11.2011 at 14:36

How do you know it’s 120 and not 90?

2. 11.11.2011 at 17:37

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?

• 12.11.2011 at 16:47

mark :

So, there are 3 squares for every 90 degrees.

Wrong. 180 degrees.

3. 12.11.2011 at 16:50

DB :

How do you know it’s 120 and not 90?

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