hnc question 2

Discussion in 'Homework Help' started by redshaw, Jul 21, 2008.

  1. redshaw

    Thread Starter Member

    Jul 15, 2008
    hello again

    a sinusoidal current is specified by the expression, i=0.1 sin (200 pie t +pie/2)

    determine a.) the peak value of the current, b.) the frequency of the current, c.) the phase angel, and , d.) the instantaneous value of the current at t=5 milliseconds (use radian measure)

    for a i have

    i=0.1 sin(200 pie t + pie/2)
    i=0.1 sin(200 pie 0.005 + pie/2)
    i= 0.1 sin (3.142 +1.57)
    i=0.082 peak to peak


    b.) f= 1/t
    f=200 Hz

    could you tell me if i am correct thus far

    for c.) i have found the equation sin(t+pie/2)=cos(t)

    is that correct one to use, if so how do i impliment it?

    for d.) not sure what to do there - any help would be greatly appreciated

    cheers guys
  2. silvrstring

    Active Member

    Mar 27, 2008
    For a sinusoidal waveform, i(t)=A*sin(omega*t+theta) where:

    A is your peak value

    omega is 2*pi*freq.

    t is time (5 msecs in your case). Just plug it in and solve.

    theta is the phase shift. You don't need trig identity sin(theta + pi/2)=cos(theta).

    Resolve your problem with this info.