   Glossary L
Lag: 1. A time delay between the output of a signal and the response of the instrument to which the signal is sent. 2. A time relationship between two waveforms where a fixed reference point on one wave occurs after the same point of the reference wave.

Large Scale Integration (LSI): The combining of about 1,000 to 10,000 circuits on a single chip. Typical examples of LSI circuits are memory chips and microprocessor.

LCD: Liquid Crystal Display - a reflective display that requires very low power for operation.

L-C Oscillator: Oscillator in which the frequency determining components are an inductor and capacitor.

LDR: Short for Light Dependent Resistor. A layer of Cadmium Sulphide material that changes resistance according to the amount of light falling on it.

Leakage: The passage of electric current that is unintended.

LED: Light Emitting Diode. A diode that emits light when current is passed through it. It has two leads: cathode (k) and anode.

Least-squares Line: The straight line for which the sum of the squares of the residuals (deviations) is minimized.

Linearity: The closeness of a calibration curve to a specified straight line. Linearity is expressed as the maximum deviation of any calibration point on a specified straight line during any one calibration cycle.

Liquid Junction Potential: The potential difference existing between a liquid-liquid boundary. The sign and size of this potential depends on the composition of the liquids and the type of junction used.

Load: The electrical demand of a process expressed as power (watts), current (amps) or resistance (ohms).

Load Impedance: The impedance presented to the output terminals of an instrument by the associated external circuitry.

Logarithmic Scale: A method of displaying data (in powers of ten) to yield maximum range while keeping resolution at the low end of the scale.

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

LS-TTL Unit Load: A load with LS-TTL voltage levels, which will draw 20 µA for a logic 1 and -400 µA for a logic 0.

LSD (Least-Significant Digit): The rightmost active (non-dummy) digit of the display.