# ACCELERATION-ERROR CONSTANT

The ratio of the acceleration of a controlled variable of a servomechanism to the actuating error when the actuating error is constant.

## Related Terms

### GEARBOX

A system of gears which alter the ratio between the revolution of the engine and the propeller shaft so the propeller operates in a relatively efficient speed range. By using a gearbox the engine and the propeller shaft will revolve at different speeds.

### AMPLIFICATION

1. An increase in signal magnitude from one point to another, or the process causing this increase.
2. Of a transducer, the scalar ratio of the signal output to the signal input

### DIRECTIVITY FACTOR

1. The ratio of radiated sound intensity at a remote point on the principal axis of a loudspeaker or other transducer, to the average intensity of the sound transmitted through a sphere passing through the remote point and concentric with the transducer; the frequency must be stated.
2. The ratio of the square of the voltage produced by sound waves arriving parallel to the principal axis of a microphone or other receiving transducer, to the mean square of the voltage that would be produced if sound waves having the same frequency and mean-square pressure were arriving simultaneously from all directions with random phase; the frequency must be stated.

### FORM FACTOR

1. The ratio of the effective value of a periodic function, such as an alternating current, to its average absolute value.
2. A factor that takes the shape of a coil into account when computing its inductance. Also known as the shape factor.
3. The theoretical stress concentration factor for a given shape, for a perfectly elastic material.

### POISSON RATIO

The ratio of the transverse contracting strain to the elongation strain when a rod is stretched by forces which are applied at its ends and which are parallel to the rod's axis.

### PLATE MODULUS

The ratio of the stress component Txx in an isotropic, elastic body obeying a generalized Hooke's law to the corresponding strain component Sxx, when the strain components Syy and Szz are 0; the sum of the Poisson ratio and twice the rigidity modulus.

### PLANT FACTOR

The ratio of the average power load of an electric power plant to its rated capacity. Also known as capacity factor.

### PHOTOELECTRIC CONSTANT

The ratio of the frequency of radiation causing emission of photoelectrons to the voltage corresponding to the energy absorbed by a photoelectron; equal to Planck's constant divided by the electron charge.

### PHASE MARGIN

The difference between 180 and the phase of the loop ratio of a stable system at the gain-crossover frequency.

### PERFORMANCE INDEX

The ratio of standard hours to the hours of work actually used; a ratio exceeding 1.00 (or 100) indicates subsoil and rocks in which the contained water is permanently frozen.

### Related questions

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