Understanding Electronics: Resistors, Capacitors, and Semiconductors
Electronics Fundamentals
Electronics is a relatively new branch of technology.
Fixed Value Resistors
A resistor is an electronic component that reduces the flow of electrons in a circuit.
Why Use Resistors?
Resistors are electronic components that reduce the flow of electrical current.
Variable Resistors
- LDR (Light Dependent Resistor): A device activated by light, like street lampposts.
- Thermistors: Resistors that vary their resistance with temperature. Used in thermostats.
- Potentiometers: Resistors with adjustable resistance via a dial.
Capacitors
Capacitors store electrical energy, though not in large amounts. They consist of two conductor plates separated by a dielectric. Electrons accumulate on the negative plate, repelling each other.
Types of Capacitors
- Dielectric
- Film
- Ceramic
- Electrolytic
Applications of Capacitors
Capacitors are used in electronic circuits for various reasons:
- To block direct current (DC) while allowing alternating current (AC) to pass.
- To filter interferences.
- To filter different frequencies.
- To smooth the current from power supplies.
- To store energy. When used for energy storage, a capacitor is called a ‘cell’. A battery is a group of cells connected in series.
Semiconductors
Semiconductors are materials with variable electrical resistance. The most common are silicon and germanium.
Diodes
Diodes allow current to flow in one direction but block it in the opposite direction. They have two parts: the anode and the cathode, each made of a different semiconductor material.
Diode Bridge
One application of diodes is the diode bridge, also called a bridge rectifier. It converts alternating current (AC) into direct current (DC).
LEDs (Light Emitting Diodes)
LEDs are a special type of diode that emits light when current flows through them. They are more energy-efficient than energy-saving light bulbs and last longer.
Transistors
A transistor is an electronic component that amplifies small electric currents or switches them on or off. It has three terminals: V (connected to a controlling current), C (connected to a source of DC current), and E (connected to the output).
Applications of Transistors
Transistors are used as switches or amplifiers. As switches, they allow or stop current flow.
Electricity Basics
Electricity is a form of energy.
Electric Current
Electric current is the movement of electrons along a conductor. Electrons jump from one atom to another. More moving atoms mean a more intense current.
Electric Tension (Voltage)
Electric tension is the difference in electrical potential between two points in a circuit. The unit of tension is the volt.
Electrical Resistance
Electrical resistance is the force that opposes the flow of electrons. The unit of resistance is the ohm.
Electrical Power
Electrical power is the product of current and voltage.
Electrical Circuits
Components include: power source, wires, and appliances.
Types of Circuits
- Series Circuits: Resistors connected one after another along the conductor.
- Parallel Circuits: Resistors connected in separate branches of the circuit.