Discussion in 'Electrical Forum discussion & Blog' started by Amy 212, May 7, 2008.

1. ### Amy 212New Member

Joined:
May 7, 2008
I donâ€™t understand how to solve this question -

â€œFind the sinusoid magnitude and phase â€œin degreesâ€ at 0.5 ms for this

V(t)= 5 sin (2π * 500 t + π/4 ) [V]

Thanks alot ...
Amy212

2. ### arfellerMember

Joined:
Aug 25, 2007
Location:
Port Angeles, WA
Is that symbol after the "2?" and "?/4" PI?
And can we assume the units of t is seconds?

Last edited: May 8, 2008

4. ### jimboPlumber

Joined:
Aug 31, 2004
Location:
San Diego
This is a straight forward solution. You just don't have all the information.

I don't specifically recognize or remember that equation from my electrical/electronic school days. But it would make sense if your "n" was pi. You have given t as 0.5 ms, so all you need to plug in a value for V and git'r'done.

5. ### MikeyAspiring Old Fart, EE, computer & networking geek

Joined:
Nov 8, 2005
Occupation:
Consumer
Location:
Central Florida
The formula as given is a little confusing, what with that [V] term dangling out there. If we assume t in seconds, and [V] just some arbitrary constant, you could express your answer in terms of [V]. All you really have to do is find the value of the sine function for t=.0005 seconds, which turns out to be .707. Thus the answer would be 3.535[V], but again I have no idea how to interpret the [V] term...

For t=.0005, the argument of the sine function evaluates to 0.5pi + pi/4 = 3*pi/4. Since 2pi radians = 360 degrees, the phase is 135 degrees. This is consistent with the value of the sine function, 0.707, which is the value of a sine function at any multiple of 45 degrees.

Was [V] originally written as |V|, by any chance? That would make sense.

Last edited: May 8, 2008
6. ### Amy 212New Member

Joined:
May 7, 2008
Hi guys;

I sorry;

V(t)= 5 sin (2pi * 500 t + pi/4 ) [V]

My problem i do not understand what "magnitude" mean?

And thanks again.

Last edited: May 8, 2008
7. ### MikeyAspiring Old Fart, EE, computer & networking geek

Joined:
Nov 8, 2005
Occupation:
Consumer
Location:
Central Florida
Magnitude would be the value of the function. For example, the magnitude (value) of a sine wave can be anything from -1 to +1. In my answer above, the magnitude of the function V(t) for t=.0005 was 3.535.