1. The ratio of heat produced in a combustion process to the heat that would be produced if a combustion were complete.
2. The ratio of heat that is actually developed in a combustion process to the heat that would be released if the combustion were perfect.

An electrode through which the electron stream (beam) passes.

This includes the ratio of the average stream current through the electrode to the stream current approaching the electrode.

1. A relation in degree or number between the power at a given frequency which is delivered by an electron stream to an oscillator or amplifier to the average power supplied to the electron flow.
2. The ratio of the power at a desired frequency, delivered by an electron flow or stream to the circuit in an oscillator or amplifier circuit and then to the average power supplied to the stream of data from a source.

The efficiency with which a motor vehicle converts energy into movement.

Not necessarily equivalent to fuel economy, in that one vehicle might have better technology and therefore be more efficient than another, but if it is much larger and heavier than the other vehicle, it would have poorer fuel economy.

The ratio of the radiant energy sensed by the average human eye at a particular wavelength to that received: The ophthalmologist, Dr. McMahon, was requested to determine the luminous efficiency of his patient, Mr. Jones, who appeared to have difficulty perceiving particular colors.

1. The ratio between the brake (useful) horsepower and the indicated horsepower of an engine.
2. The measure of the effectiveness with which a system performs.

It is stated as the ratio of a system's work output to its work input.

In a theoretically frictionless, or ideal, machine, the work input and the work output are equal, and the efficiency would be 1, or 100%.

The percentage of the total available light captured by plants that is subsequently converted into chemical energy.

The ratio of the electric power produced by a photovoltaic device to the power of the sunlight incident on the device.

1. A measure of the efficiency of converting a fuel to energy and useful work.
2. An expression of the effect of temperature on the rate of plant growth; assuming other condition are satisfactory.
3. The ratio of the amount of work performed by a heat engine in one cycle to the amount of thermal energy input required to operate the engine over one cycle; a measure of the efficiency of converting a fuel to energy and useful work.