# Glossary of Terms - L

### Laws of Thermodynamics

Heat energy can be changed in form and transferred between objects but cannot be created or destroyed. Heat energy flows from a hotter to a cooler body. Absolute zero can never be attained.

### Limits of Error

The deviation in degrees or % of Standard or Special grade thermocouples in EMF outputs from an ideal calibration. This tolerance or calibration normally applies only from 0°C up to the maximum temperature for each thermocouple. Sub-zero limits require special calibrations.

### LCD Display

In digital instruments, a numerical readout in which the digit segments are delineated by dark areas in a liquid-crystal display.

Connecting leads can affect the accuracy of small current transformers, DC shunts and low voltage analog voltmeters. Use leads supplied with device or lead size specified.

### LED Display

In digital instruments, a numerical readout in which the digit segments are delineated by light-emitting diodes.

### Linearity

A measure of the departure from a straight-line response in the relationship between two quantities, where the change in one quantity is directly proportional to a change in the other quantity. Usually expressed as a maximum percent. Rotational displacement in analog meters, particularly for low-level measurements and/or AC parameters, is distinctly non-linear with respect to changes in the quantity under measurements; accuracy in these cases is maintained by means of properly calibrated non-linear scale cards.

### Loop Resistance

The electrical resistance, in ohms, of a complete thermocouple circuit exclusive of an instrument's internal resistance.

### Least-Significant Digit (LSD)

The rightmost active (non-dummy) digit of the display.

### LS-TTL Compatible

For digital input circuits, a logic 1 is obtained for inputs of 2.0 to 5.5V, which can source 20 µA, and a logic 0 is obtained for inputs of 0 to 0.8V which can sink 400 µA. For digital output signals, a logic 1 is represented by 2.4 to 5.5V with a current source capability of at least 400 µA; and a continued - logic 0 is represented by 0 to 0.6V with a current sink capability of at least 16 mA. "LS" stands for low-power Schottky.