Who can explain this?
A DC power supply vs. AC power supply according to the attached picture having the same load, the same current and voltage on it, but different power distributed on resistor.
Practically I configured the electric circuit and measured its parameters, both for DC and AC with almost the same results as well as into the simulation (I used NI MultiSIM v.11.0.1).
Is anybody able to prove that I’m wrong somewhere?
And what’s wrong here?!
I'm waiting your comments by sending mails to: <email.sorin@yahoo.com>
A lot of thanks in advance !
Hi there,
Think about this for a moment. You've got an energy storage element in one circuit but not in the other. The peak voltage gets partially stored in the cap in one circuit, but not in the other. Which one should show more power dissipated in the load?
Dont increase the value of the cap, instead, remove it entirely and test again.
DC meters usually average the input, which is not the same as measuring power. It doesnt matter if the average voltage is the same, sometimes it doesnt even matter if the rms reading is the same, because power is defined as the voltage times the current averaged over time. Without doing an exact analysis, here is the difference:
PowerFirstCircuit=avg(v(t)*i(t)) with the constraints avg(v(t))=K1 and avg(i(t))=K2,
PowerSecondCircuit=avg(v(t))*avg(i(t)) with the constraints avg(v(t))=K1 and avg(i(t))=K2,
So we see in the first case we first multiply, then take the average, but in the second case we first take two averages and then later multiply. We have two constraints but they are really kind of arbitrary and not as important as they may appear to be at first. The important point is that if we calculate power differently in each case we will get a different answer in each case.
You would do yourself a favor to look into other cases like these two also, especially pulse circuits. Pulse circuits show very clearly the differences like this.
We can do an exact analysis if you prefer to show the difference.