Can the formula U U R calculate the power rating?

p=ui is absolutely universal!

However, compared to p=u*u r, it is the same meaning for purely resistive load circuits. Not for inductive load circuits!

p=ui=u*(u r) The difference is that one knows the current, the other knows the resistance, and the pure resistive circuit finds i through the resistance according to Ohm's law, and then transforms it into p=u*u r=ui, and the result is calculated and the correct solution is solved.

However, there is a difference for inductive load circuits, for example, there is a motor in the circuit, and the motor does have its resistance (internal resistance), but it should be noted here that the current of the motor can no longer be calculated by Ohm's law, but according to the conservation of energy, the mechanical power of the motor is more, then its current is large, Ohm's law is no longer applicable here, and it is impossible to draw an equal sign between the current I and U r through the motor!

u*u r and ui mean the same thing.

i=u r, so u=u*u r.

Under the rated voltage of the appliance, the rated power of the appliance is calculated according to this formula.

You're asking a formula that can be used for junior high school or some high school questions, because they're all purely resistive circuits. When adding inductive loads, it is not used, such as inductive capacitors, because inductive loads do not do mechanical power!!

1: When the total current and total resistance of the circuit are known, use: i r is applicable to the series circuit, because the series circuit current is equal everywhere, 2: when the total voltage of the circuit is known, and the total resistance, use: u r is applicable to the parallel circuit, because the total voltage of the parallel circuit is equal.

3: When calculating the power of the local circuit, i, r, u are known, and when two of the quantities are known, the power of the part can be calculated, p=i r=u r=ui

In general, 1) when the resistors are connected in series, the current on the resistor is equal, and the power is calculated by ir;

2) When the resistors are connected in parallel, the voltage applied to the resistors is equal, and the power is calculated by u:r.

The output power of the power supply is measured at the output end of the power supply, and there are two calculation formulas, and you can choose one arbitrarily according to your own situation:

1. P=U*i, measure the output voltage and output current, and the result is the output power.

2. P=U 2 R (the square of U divided by R), this method is suitable for output power measurement under pure resistive load conditions. If you are AC output, it is calculated with the RMS value of u.

The total power of the power supply = the output power of the power supply + the loss of the power supply itself, the measurement method is at the input end of the power supply (note, not the output end), measure the voltage and current at the input end, and then multiply to the total power. The total power measured here is definitely greater than the output power.

Then you can also calculate that p output p total * 100%, and the result is the efficiency of the power supply.