8.1. ELECTRIC COMPONENTS
Here, we'll analyse the most common electronic components.
Fixed resistance or resistor
A fixed resistance or resistor opposes the flow of electric currents. Its value, which we measure in ohms is indicated by a code of colours and numbers.
The first two stripes are replaced by two numbers, according to their colour.The third stripe indicates the number of zeroes that we must add to the previous figure.The fourth stripe indicates the tolerance or the maximum deviation from the theorical value.
Variable resistance or potentiometer
The value of a variable resistance or potentiometer can be adjusted between zero and the maximum value specified by the manufacturer.
Resistance that depends on a physical factor
There are two types of resistances that depend on a physical factor:
-Resistance that depends on temperature, that is called a thermistor. There are two types of thermistors:
-Negative temperature coefficient (NTC):The resistance decreases as the temperature rises.
-Positive temperature coefficient (PTC): The resistance increases as the temperature rises.
-LDR: Resistance that varies according to the amount of ligth received.The resistance decreases as the amount of ligth increases. These devices ,like potentiometers, are often used in security systems, where they are parts of sensors.
Capacitors
A capcitor can store electrical energy from a battery and then use it to power a ligth bulb until the charge is totally depleted.
Capacitors are componets that can store an electrical charge.
The value of a capacitor indicates the charge in volts that it can store.This is measured in farads (F).
Diodes
A diode is an electronic component made from semiconductor materials.It only allows electric current to flow in one direction. A diode has two electrodes: an anode(A) and a cathode (K).
A LED (ligth emitting diode) only gives off ligth when an electric current flows through it.
No hay comentarios:
Publicar un comentario