Digital Multimeter M300C

Voltage(symbol: V), also called electromotive force, is a quantitative expression of the potential difference in charge between two points in an electrical field.

An electric current is a flow of electric charge. The common symbol for current is the uppercase letter I. The SI unit for measuring an electric current is the ampere(A), which is the flow of electric charge across a surface at the rate of one coulomb per second. The particles that carry the charge in an electric current are called charge carriers.

Resistance is the opposition that a substance offers to the flow of electric current. It is represented by the uppercase letter R. The standard unit of resistance is the ohm(Ω)

In electronics, a continuity test is the checking of an electric circuit to see if current flows . A continuity test is performed by placing a small voltage across the chosen path. If electron flow is inhibited by broken conductors, damaged components, or excessive resistance, the circuit is "open".

A diode is a specialized electronic component with two electrodes called the anode and the cathode. Most diodes are made with semiconductor materials such as silicon, germanium, or selenium. The fundamental property of a diode is its tendency to conduct electric current in only one direction. When the cathode is negatively charged relative to the anode at a voltage greater than a certain minimum called forward breakover, then current flows through the diode. If the cathode is positive with respect to the anode, is at the same voltage as the anode, or is negative by an amount less than the forward breakover voltage, then the diode does not conduct current. This is a simplistic view, but is true for diodes operating as rectifiers, switches, and limiters. The forward breakover voltage is approximately six tenths of a volt (0.6 V) for silicon devices, 0.3 V for germanium devices, and 1 V for selenium devices.

The indication for low battery level is a useful feature and alert the user when needed battery unit to be changed. So you will still have a functioning device for use.