# Basic Electronics

## 40 terms

### Rheostat

Varable resistor with two terminals to vary current (I).

### Thermistor

Thermally sensitive resistor whoes resistance has an non linear value change with changes in operating temperture.

### Potentiometer

Variable resistor with three terminals connected as a volt divider.

### Hole

Positive charge that exists only in doped semiconductors because of convalent bonds between atoms. The amount of hole charge is the same as that of a proton and electron.

### Ion

Atom or group of atomes with net charge. Can be produced in liquids, gases, and doped semiconductors

### polarity

Property of electric charge and voltage.

### Hole Current

Motion of hole charges. Direction is the same as that of conventional current.

### Nagative polarity

Is an excess of electrons

### Positive polarity

Deficiency of electrons

### Negative temperature coefficient (NTC)

Thermister resistance decreases as its operating temperture increases

### Positive temperature coefficient (PTC)

Thermister resistance increases as the operating temperature increases.

### Ohm's law

The amount of current in a circuit is directly proportional to the amount of voltage applied and inversly proportional to the amount of resistance.

### zero

How much resistance is measured in a short circuit

### Infinite

How much resistance is measured in an open circuit.

### Kirchhoff's Voltage Law

In a series circuit the sum of all the resistor voltage drops equal the applied voltage.

### Potential

The ability to do work in moving another charge. Measured in Volts

### Kirchhoff's current law

In an parallel circuit the total current in the main line equals the sum of the individual branch currents.

### Short circuit

Has practically zero resistance

### Open circuit

Has infinite resistance

### Varistor

A resistor whose resistance varies in proportion to the voltage of the current through it.

### Wheatstone bridage

A circuit that is used to determin the value of an unknown resistance

### Standard resistor

A precision resistance variable 0-9999 in 1 ohm steps.

### Ratio arm

Two resistors with precision resistances use to determin the value for an unknown resistance.

Measured voltage decreases because of an additional load current through the meter

### Meter shunt

A precision resistor connected across the meter movement for the purpose of bypassing a specific fraction of circuit's current around the meter movement.

### ohms-per-volt rating

Specifies the sensitivity of a meter in all voltage ranges. The higher the number the better.

### Node

A junction, connection or terminal within a circuit were two or more circuit elements are connected or joined together giving a connection point between two or more branches.

### Branch

Is a single or group of components such as resistors or a source which are connected between two nodes

### Loop

Is a simple closed path in a circuit in which no circuit element or node is encountered more than once.

### Mesh

Is a single open loop that does not have a closed path. No components are inside a mesh.

### Permeability

The ability to concentrate magnetic flux

### Relative permeability

The ratio of permeability of a medium to that of free space

### Flux

Magnetic lines of force

### Flux density

Amount of flux per unit area

### Solenoid

A coil of wire designed to produce a magnetic field when energized.

### Lenz' law

The direction of induced current must be such that its own magnetic field will oppose the action that produced the induced current.

Vind= N(ΔΦ/Δt)

### Induction

Current produced by magnetic forces without physical contact.

### Torque

Any force or system of forces that causes or tends to cause rotation

### Inductance

The characteristic that opposes any change in current.

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