Signal Voltage

Hi all, this is my first post

I'm doing HNC Electrical Engineering and I've come across this one question that im struggling with a little.

You know that the signal takes the following form:
𝑣 = 𝑉𝑝 sin (2𝜋 ft − ∅)

Taking measurements from the oscilloscope display above, determine 𝑉p, 𝑓,and ∅, and insert those values into the above equation.

Now rearrange your new equation to make the time t, the subject of this formula and hence determine, to within 3 decimal places, the first point in time when the voltage waveform has a magnitude of 5.25
volts.
Assuiming 𝑣 = 5.25

I have rearranged the formula:
t = asin((5.25/7)+∅)/2𝜋(f)

Am I along the right lines? Any help would be appreciated.

Reply 1

Ferret!

6

My advice is to do algebra first, then substitute numbers later.

Rearrangement

(edited 8 months ago)

Original post by mint-mouse

Hi all, this is my first post

I'm doing HNC Electrical Engineering and I've come across this one question that im struggling with a little.

You know that the signal takes the following form:
𝑣 = 𝑉𝑝 sin (2𝜋 ft − ∅)

Taking measurements from the oscilloscope display above, determine 𝑉p, 𝑓,and ∅, and insert those values into the above equation.

Now rearrange your new equation to make the time t, the subject of this formula and hence determine, to within 3 decimal places, the first point in time when the voltage waveform has a magnitude of 5.25
volts.
Assuiming 𝑣 = 5.25

I have rearranged the formula:
t = asin((5.25/7)+∅)/2𝜋(f)

Am I along the right lines? Any help would be appreciated.

I would do one step to correct your mistake:

\sin^{-1}\left ( \frac{v}{V_p} \right ) = 2 \pi ft - \phi

Now treat the term on the left-hand side as a constant say alpha, and make time t the subject.

\alpha = 2 \pi ft - \phi

Reply 3

Glendular

1

Original post by mint-mouse

Hi all, this is my first post
I'm doing HNC Electrical Engineering and I've come across this one question that im struggling with a little.
You know that the signal takes the following form:
𝑣 = 𝑉𝑝 sin (2𝜋 ft − ∅)
Taking measurements from the oscilloscope display above, determine 𝑉p, 𝑓,and ∅, and insert those values into the above equation.
Now rearrange your new equation to make the time t, the subject of this formula and hence determine, to within 3 decimal places, the first point in time when the voltage waveform has a magnitude of 5.25
volts.
Assuiming 𝑣 = 5.25
I have rearranged the formula:
t = asin((5.25/7)+∅)/2𝜋(f)
Am I along the right lines? Any help would be appreciated.

Hi, it looks like I am doing the same course as you. What figure did you settle on for t1? The exact point at which the wave crosses the midline is a bit ambiguous....

Reply 4

mint-mouse

OP

2

Original post by Glendular

Hi, it looks like I am doing the same course as you. What figure did you settle on for t1? The exact point at which the wave crosses the midline is a bit ambiguous....

I was thought that too i estimated it was either 0.0000325 or 0.000033