could any one help us with this i have no idea where to start Find the instantaneous value of a 50 Hz waveform with a maximum value of 200v. 0.001 sec after it has passed through a voltage zero. many thanks . liam
v=Asin(2πft) where v is the instantaneous voltage A is the peak (maximum) voltage f is the frequency t is the time so v=200sin(2πx50x0.001) =1.097 Volts You said when it has passed through zero: so it may be positive like + 1.098 or negative like - 1.097
Right. So you get 200sin(pi/10), or 200sin(18degrees). Both are 61.8V, right? Am I doing something wrong?
The dimensional analysis is: t in seconds. 2*PI = radians/cycle f = cycles/sec. 2*PI*f*t = radians/cycle * cycles/sec * sec = radians. So, take the sine in radians. The 61.8 magnitude is correct.
Thanks for the replies guys. but im still none the wiser as were you got the answer from . i understand that the answer is 61.8v. but where did this come from . when i tried working out the equation v=200sin(2πx50x0.001) =1.097 Volts i got - 0.107 ????
Okay, step by step 1. 2*PI radians/cycle * 50 cycles/second * 0.001 seconds = 0.314 radians This is just stating that 0.001 seconds into a 50Hz sine wave is 0.314 radians in. 2. Take the sine of this, but remember to set up your calculator to calculate your trigonometric functions in radians. So, sin(0.314 radians) = 0.309 Just so you understand, what this says is that at 0.001 seconds into a 50Hz sine wave, the voltage is 0.309 times the peak. 3. Multiply by the peak voltage, 200V. 200V*0.309 = 61.8V. Got it?