ahhh make sense a bit !!Go back to basics.
V = L di/dt
so 40V ? is that right?Check the time scale.
And here is a shining example of why I am always screaming about units!ahhh make sense a bit !!
so answer is 0.002 * (20/1) = 0.04 for VL
And here is a shining example of why I am always screaming about units!
The answer is NOT 0.002 * (20/1) = 0.04, it is
0.002H * 20A / 1ms = 0.04 HA/ms
You don't have to remember what the base units are for henries or farads, just use the formulas:
V = L di/dt => V = HA/s => H = Vs/A
Q = CV =? F = C/V = Cs/Vs = As/V
0.04 HA/ms = 0.04 (HA/ms) (1000/m) (Vs)/(HA) = 40V
Or even more simply:
2mH * 20A / 1ms = 40 (HA/s)(Vs)/(HA) = 40V
The majority of mistakes that you will make will mess up the units -- just like happened here. If you track your units, you will catch most of these mistakes when you make them. If not, you just blindly accept a wrong answer and next thing you know you have just applied 40V to something that you were expecting would see 40mV and some piece of flight-critical hardware has just gone bye-bye and the planeload of passengers is now at the bottom of a smoking crater.
No, both are wrong. You need to check it again.am i right?
yeah i know voltage in resistor doesn't go above 40 and -40 but i dont get it with the inductor ?No, both are wrong. You need to check it again.
VR = I* R and because R is constant VR and IR has the same shape.
UL = Ldi/dt and you need to consider i in each time periods.
What is a voltage of 40?yeah i know voltage in resistor doesn't go above 40 and -40 but i dont get it with the inductor ?
is it right?What is a voltage of 40?
What is a height of 3?
What is a weight of 10?
What is a volume of 6?
What is a speed of 13?
Do any of these make any sense to you?
Quit being sloppy about the units. That, or get the hell out of engineering. What would you say should happen to a doctor that didn't bother to check his units and ended up prescribing someone a thousand times more of a medicine than they should have and the person died as a result? Oh, but you say, if a doctor makes a mistake they could kill some one. Well, doctors are generally limited to killing people one at a time. Engineers that can't be bothered to use simple and effective error detecting procedures in their work kill people in job lots.
The voltage in the resistor does not exceed +40V or -40V.
Units matter.
You've already found that, between t=0s and t=1ms, that the voltage across (not "in", you also need to start using the proper terminology to minimize miscommunication) the inductor was 40V. So why does your graph show it changing in this time period?
What is the voltage across an inductor if the current isn't changing?
Is the current changing in the inductor in the time periods 1ms<t<2ms or 4ms<t<5ms?
What is the voltage across the inductor during these time periods?
Is this consistent with your chart?
You need to not only start tracking and checking your units, but you need to start always asking if your answer makes sense. Do those to things, relentlessly, and you will see your grades go up considerably and you will let far fewer mistakes get past you on the job and you will catch many of the mistakes that others did let get past them and you will be much more valuable to your employer and/or customers and you will make a lot more money and you will kill a lot fewer people.
i know it is Volt bro i didnt put in there !!!40 WHAT????
Quatloos?
Gorillas?
UNITS! UNITS! UNITS!
Other than the units issue and the fact that there is no indication (except by context) of what this is a graph of, you've got it.
I don't care whether you know it or not. I had hoped that the fact that it's already been pointed out to you that you are making mistakes and not catching them because you are being sloppy with units would make you aware of their value. But, apparently, that was wishful thinking on my part. So please consider switching to a field other than engineering where your disregard for even the simplest error detecting practices is less likely to get someone killed someday.i know it is Volt bro i didnt put in there !!!
That was my first thought, but the other thread is actually different problem. The only thing they have in common is that it is a series RLC circuit. The other problem has different component values and an AC voltage source instead of a piecewise linear current source.I find it unusual you have two threads dealing with this one problem.
Thanks for the backup.WBahn's price for helping you is you identifying the units. A cheap price. The reader could assume it was volts, or they could assume it was 40 mV, or 40 GV. The only thing for sure is it's 40 something. Attention to detail provides clarity to the reader.
Do not worry.I know I am more than a bit of a Units Nazi, but I am completely unapologetic about it. I have very sound and motivating reasons for having the attitude that I do.
by Don Wilcher
by Jake Hertz