1. ## sinusoidal function

need help with this can you provide any light on it.....

The instantaneous value of current, i amp, at t seconds is given by

i= 15 sin (100 pi t + 0.6)

Find
the amplitude
the period
the frequency
the initial phase angle when t =0 expressed in both radians and degrees
the value of i when t=2.5
the time in milliseconds when the current first reaches its maximum value

I need all the help I can get thanks

2. ## Re: sinusoidal function

For $\displaystyle y = A \sin B (x-C)$

A is the amplitude and $\displaystyle \frac{2\pi}{B}$ is the period, can you answer the first two now?

3. ## Re: sinusoidal function

no sorry can you help some more

4. ## Re: sinusoidal function

Originally Posted by gordonmckee
no sorry can you help some more
you really need to research how sinusoidal graphs are transformed ...

5. ## Re: sinusoidal function

Amplitude ---- 15

Period ---- 2 pi / 100 pi = 1/50

Frequency ---- F=1 / (1/50) = 50Hz

Phase Angle ---- 0.6 rad = (0.6 x (180/pi)) = 34.38deg or 34o 23' leading

I ----15 sin (100 pi 2.5 + 0.6) = 15 sin (786) = 15 x 0.9063 = 13.59Amps

Time ---- 15 = 15 sin (100 pi t + 0.6)

arcsin 15 / 15 = ( 100 pi t + 0.6)

100 pi t = 1.5708 - 0.6

t = 0.9708 / 100 pi

t = 0.0031

= 3.1 ms

6. ## Re: sinusoidal function

can anyone varify if i'm right on this or not
Thanks

7. ## Re: sinusoidal function

I take it I am on the right track with this then.....

9. ## Re: sinusoidal function

Originally Posted by gordonmckee
I think your on the right lines, I have just completed this question for my HNC and I have the same answers which I confirmed with my tutor today

Are you at Teeside University?

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# What is the frequency of electric current if the equation of an electric current is I=0.6sin 100^t

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