hnc question 2

Thread Starter


Joined 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


Joined 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.