AAMC FL 3, C/P, Q18 help!

[mariposas905]

For this question, why is the time period not 1500 ns? According to the time period definition for a wave shown in the attached picture, I thought we are supposed to complete one full round...so 500+500+another 500 to end where the voltage source first began (in the "up" position)

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[mariposas905]

bump, still having trouble with this q :/

 

[AdaptPrep]

Hi, mariposas905--

It takes no time to move vertically (or, it is immeasurable). So to move from down to up position, it takes no time. After 500 + 500 ns, you completed one full "wave". If you measure mid-crest to mid-crest like the example you provided, it would still be 500 + 500 (confirm this yourself so it makes sense).

Good luck!

 

[mariposas905]

Hi, mariposas905--

It takes no time to move vertically (or, it is immeasurable). So to move from down to up position, it takes no time. After 500 + 500 ns, you completed one full "wave". If you measure mid-crest to mid-crest like the example you provided, it would still be 500 + 500 (confirm this yourself so it makes sense).

Good luck!

Thanks for clarifying! But if we move mid crest to mid crest, isn't that still vertical movement? So, it would go up to 500ns first and down to 500ns and then again up to 500 ns to get to the second mid crest? Do we have to subtract the "bottom" 500ns?

Still confused

 

[AdaptPrep]

Does this help? This measures crest to crest. This shows it is 500 + 500 ns. Only look at horizontal displacement for time.

 

[mariposas905]

Does this help? This measures crest to crest. This shows it is 500 + 500 ns. Only look at horizontal displacement for time.

View attachment 237636

Ah okay, got it, thank you. So, crest to crest is one wavelength, but when it comes to time, we only look at horizontal distance, not the vertical ones. I was getting confused because I thought the bottom 500 ns was also considered as a horizontal distance. So I added it as 3 horizontal distances (two upper 500s + bottom 500). I guess it's like we need to subtract the bottom one from the top two.

 

[AdaptPrep]

This might help too.

The upper and bottom are all equivalent and should not be read as upper or bottom. Just move the frame of reference for any period. For example, this is also one period:

It does not matter if the 500 ns was written on top or bottom...it is only to show the scale of the x-coordinate. I listed it three times just to show you that the distance is the same if it is written on top or bottom. Just focus on the horizontal distance in one complete period to get the time. Yellow arrow to yellow arrow is 1000 ns no matter where the frame of reference of one period is.