## Electronics Information Flash Card Set 149326

 Cards 10 Topics Battery Configurations, Conductors, Direct Current (DC), Insulators, Resistance, Resistors, Semiconductors, Transformers, Transistors, Voltage

#### Study Guide

###### Battery Configurations

Batteries can be connected together in various combinations to increase their total voltage and/or total current. Connecting batteries in series combines their voltage while keeping their current the same, connecting batteries in parallel combines their current while keeping their voltage the same, and using a series-parallel configuration, half the batteries can be connected in series and half in parallel to combine both voltage and current.

###### Conductors

Conductors are elements that allow electrons to flow freely. Their valence shell is less than half full of electrons that are able to move easily from one atom to another.

###### Direct Current (DC)

Direct current flows in only one direction in a circuit, from the negative terminal of the voltage source to the positive. A common source of direct current (DC) is a battery.

###### Insulators

Insulators have valence shells that are more than half full of electrons and, as such, are tightly bound to the nucleus and difficult to move from one atom to another.

###### Resistance

Resistance is opposition to the flow of current and is measured in ohms (Ω). One ohm is defined as the amount of resistance that will allow one ampere of current to flow if one volt of voltage is applied. As resistance increases, current decreases as resistance and current are inversely proportional.

###### Resistors

Resistors are used to limit voltage and/or current in a circuit and can have a fixed or variable resistance. Variable resistors (often called potentiometers or rheostats) are used when dynamic control over the voltage/current in a circuit is needed, for example, in a light dimmer or volume control.

###### Semiconductors

Semiconductors have valence shells that are exacly half full and can conduct electricity under some conditions but not others. This property makes them useful for the control of electrical current.

###### Transformers

A transformer utilizes an inductor to increase or decrease the voltage in a circuit. AC flowing in a coil wrapped around an iron core magnetizes the core causing it to produce a magnetic field. This magnetic field generates a voltage in a nearby coil of wire and, depending on the number of turns in the wire of the primary (source) and secondary coils and their proximity, voltage is induced in the secondary coil.

###### Transistors

The transistor is the foundation of modern electronic devices. It is made entirely from semiconductor material (making it a solid state device) and can serve many different functions in a circuit including acting as a switch, amplifier, or current regulator. A transistor works by allowing a small amount of current applied at the base to control general current flow from collector to emitter through the transistor.

###### Voltage

Voltage (V) is the electrical potential difference between two points. Electrons will flow as current from areas of high potential (concentration of electrons) to areas of low potential. Voltage and current are directly proportional in that the higher the voltage applied to a conductor the higher the current that will result.