Electricity and direct current circuits
Electricity
Electric current
Is a form of energy that lets negatively charged particles.
Is the flow of electrons from one atom to another inside a conductive material.
Components of electric circuits
Is a series of interconnected components that an electric current flows through to produce an effect.
Power sources
Control devices
Components that supply the necessary electrical energy to the rest of the circuit in order to move the electrons. The generatorsof direct current in a circuit are cells and batteries.
Load devices
Conductors
Components that transport the elctrical energy from the power sources to the load devices; in other words, the electric current flows through these components. The conductve components of a circuit are the wires.
Components that receive the electrical energy from the power sources and convert it to other types of useful energy. Examples of load devices in circuits are: motors, buzzers and resistors.
Insulators
Conductors
Materials that do not let electric current flow through them.
Materials that let electric current flow through them.
Devices that regulate the circuit; in other words, they allow or prevent the flow of electric current through the circuit. The main types of control devices are one-way switches, push switches and two-way switches.
Cell: Supplies electrical energy to the rest of the circuit.
Cells have a positive terminal and a negative terminal; this lets them supply electric current to the circuit when they are connected.
Battery: A grouped set of cells.
Lamp: Converts electrical energy to light energy.
Buzzer: Converts electrical energy to sound energy.
Motor: Converts electrical energy to kinetic energy.
Resistor: A load device that opposes the flow of the electric current. Converts electrical energy to heat energy.
Wire: The component that the electric current flows through.
Control devices:
Push switch
Two-way switch
One-way switch
Electrical schematics
We represent electrical cicuits with a very simple drawing called an electrical schematics. Every component in a circuit has a standardised symbol to represent it in a simple way that anybody can understand. The symbolic representations of each of the circuits components mentioned above are shown on the following pages.
Open and close circuits
A cicuit is open whent the energy of the power source cannot reach the load devices, so the electric current cannot flow. This can happen if the switch is open, but it can also be because of a fault in the circuit.
A circuit is closed when the energy of the power source reaches the load devices, so the electric current flows.
Types of circuits
Parallel circuits
Series circuits
Series-parallel combination circuits
Main electric variables:
Voltage: This is the different in the charge between two points, wich makes the electrons move. When we connect a cell to a circuit, there is a potential difference between the two ends of the cells, wich forces the electrons to move. Its unit of measurement in the International System is the volt.
Resistance: This is the opposition to the flow of the electric current. Its unit of measurement in the International System is the ohm. The components of a circuit that put up the most resistance are the load devices.
Current: This is the intensity of the current or the amount of electrons flowing through a conductor over a certain time. Its unit of measurement in the International System is the ampere or amp (A).
Coverting electrical enegy
Resistor... heat energy
Lamp... light energy
Motor... kinetic energy
Buzzer... sound energy