Power is the amount of work(W) done in a given amount of time(t).
Efficiency is a measure of how a machine is effective. This is done by taking the ratio of output work and dividing by the work input
e=Work/WI*100
Answer
Efficiency is the ratio of a machine's output power to its input power, usually expressed as a percentage.
A machine will always have losses, so its efficiency will always be less than 100%.
Further to the original answer, 'effectiveness' and 'efficiency' are two completely-different concepts. Effectiveness (or 'efficacy') defines whether or not a device achieves what it is designed to achieve; efficiency provides a way of defining the losses that occur while the device achieves what it is designed to achieve. For example, a motor might be perfectly 'effective' at producing rotatary movement, but it loses 5% of its input power doing so. So it is 100% effective but only 95% efficient,
The formula of efficiency is power output divided by the power input.
Efficiency = useful output power / input power
You use the definition of "efficiency": you divide output power by input power. Both of these, of course, need to be measured or calculated.
The efficiency tells you how good the machine is. Efficiency equals the power output of the machine divided by the power that is input via a shaft, or via electrical wires, or via fuel. So if the machine has a low efficiency it wastes power and energy, which costs money. The average ordinary automobile has an efficiency of 20-25%. A lot of research work goes into improving that figure.
It is around 35 to 40 %
Efficiency is output power divide by input power.
Efficiency = useful output power / input power
Efficiency = (output power/input power) x 100%
The formula of efficiency is power output divided by the power input.
Efficiency = useful output power / input power
B.) efficiency
The efficiency is output divided by input.
The efficiency of a motor is the output power divided by the input power. The difference is the lost power which appears as heat usually. High-efficiency motors produce very little lost power. But they tend to be more massive and expensive to make, so that most motor designs have to compromise on efficiency.
A high efficiency machine will produce more of what is it that you want with the same power as the low efficiency one. In other words, for a low efficiency machine do as much as a high efficiency one, you have to give it more power (energy).
Inverter efficiency varies with DC input voltage, ambient temperature, and operating power level of the inverter. It can mean power-out divided by power-in.
The efficiency of any machine is the output power divided by the input power, usually expressed as a percentage.
Generally efficiency is the ratio of the energy or power utilized usefully to the energy or power given as input to the device. So efficiency in this case = 50/75 = 2/3 Usually efficiency will be given in percentage. So multiplying 2/3 by 100 we get 66.7% as the efficiency of the machine.