Informally, this is referred to as the "power law" or "power formula". It seems that there is a widespread practice to refer to it, incorrectly, as "Watt's law". However, note that the first term potentially conflicts with a widely used meaning of "power law" which describes any situation in which two quantities are related via any any power ...

2016年6月18日 · In order to calculate power loss in the transmission lines, you need to know the power received by the load end and the voltage at the load end. Use these two to calculate the current drawn from the line. Here you use P=VI. Then use the this current value and the total resistance of the transmission line to calculate the power loss.

So the only thing we have to do is fill in the correct values in the formula. An example. We again use the \$5\text{V}\$ power supply with a \$250\Omega\$ \$\text{R}_{\text{load}}\$ and two wires of \$2.5\Omega\$ each. The voltage drop over one piece of wire is, as calculated above, \$0.049025\text{V}\$.

\$\begingroup\$ The first formula you give above is correct. You find the instantaneous power as a function of time, integrate over the time interval of interest, and divide by the length of that interval. For a time-varying voltage with an average value of 0 …

for finding out power supplied by the battery we use the formula, P = V*I; where V is the voltage across its terminal and I is current flowing out positive terminal. For finding out power consumed by the resistance of wire. we prefer, P = I^2*R; where I is the current flowing through the wire/resistance and R is the resistance offered by the wire.

2016年5月1日 · The basic formula for power is just like P = V.I except it is: - Power = pressure (pascals) x flow rate (cubic metres per second) To calculate flow rate needed to deliver 10 kW, divide power by pressure i.e. flow rate is 10/700 = 0.0143 cubic metres per second. I'll leave you to work out what it is given the motor and turbine efficiences.

2016年6月8日 · The power is 6A * 12V = 72W; or the voltage source : you have first to calculate the current flowing in the source, which is the difference between the current in the resistor and the current of the current source. I = 4A - 6A = -2A. And the power is : -2A * 12V = -24W. The minus sign tells the voltage source will RECEIVE 24W

2019年4月12日 · To get average power, you would only need to divide by the load. If x represents current, then the formula computes mean square current and you would multiply by the load to get average power over the interval. So the formula is related to power, even though it is not power. I think you can't compute power without knowing the load. \$\endgroup\$

P is the amount of power generated by the component of i(t) that's in phase with v(t). It is oscillatory but has a mean value that's equal the mean power delivered to the load. And the complex power S, the total power, is exactly the sum of these two components

2020年4月7日 · But if you consider a motor, maybe 80 or 90% of the power will be converted to kinetic energy. For an LED, maybe 20% of the power will be converted into light. If you consider a battery charger, maybe 95% of the power will be converted to stored energy in the battery. So power delivered to the load is not the same as power loss.