Capacitors and Electric Current: Understanding the Basics
Capacitors
A capacitor is a device capable of storing electric energy.
Capacitance
Capacitance is a property associated with each capacitor and measures the storage capacity of the electric charge when a potential difference is applied to its plates. Capacitance depends on several factors: the distance between the conductors, the size of the conductors, the voltage between them, and the dielectric between the objects.
Dielectric
A dielectric is an insulating material placed between the plates of the capacitor. Effects of a dielectric in a capacitor:
- Increasing the capacitance.
- Improving the mechanical stiffness of the physical structure of the capacitor.
- Decreasing the voltage between the capacitor plates, producing a diminution of this electric field.
Dielectric Strength
Dielectric strength is the maximum electric field that can be applied to the capacitor without causing electrical breakdown.
The energy stored in the plates of a capacitor. Touching the plates causes a discharge that takes place through our bodies.
Capacitors in Parallel
Two plates are connected to the positive terminal of the battery, while the other two are connected to the negative terminal. The charge received by two or more capacitors is divided between them, so that the net charge is the sum of the charges. The voltage is the same in each capacitor.
Capacitors in Series
Connect alongside it. The charge of the capacitors is the same for each one of those involved. The applied voltage is divided so that V = V1 + V2.
Dielectric Effect
By locating a dielectric between the plates of a capacitor: the polar molecules are randomly oriented in the dielectric. When introduced between the plates of a capacitor, to which an electric field is applied, the molecules tend to align in the direction of the field, and the dielectric is polarized. This creates a less intense electric field within it, which is applied but in reverse.
Electric Current
Electric current is a flow of electric charges.
Effects of Electric Current
- Light: Takes place when current flows through a conductive element, leading to increased temperature, which in turn leads to the production of visible light.
- Heat: Electric charges passing through a conductor generate heat significantly. In some specific devices such as toasters, irons, heaters, etc.
- Chemical: The decomposition of electrolyte solution in batteries, metal coatings such as chrome, etc., are important applications of electric currents.
- Magnetic: Any movement of electric charges has associated magnetic effects. One important application of this effect is found in electromagnets used for lifting heavy metal objects.
- Dynamic: The interaction of electric current with a magnetic field gives rise to mechanical movements.
Sources of Power
- Thermoelectricity: When you have large amounts of heat, electricity can be obtained through the use of steam plants.
- Piezoelectricity: Some non-conductive materials have the ability to produce a voltage between the surfaces when mechanical stress is applied (crystals, microphones).
- Photoelectric effect: Refers to the emission of electrons from a metal surface as a result of an incident light beam on the surface.
- Chemical action (Batteries): Batteries are devices that convert chemical energy into electrical energy.
- Magnetic field action: When there is an interaction between a closed electrical circuit with a moving magnetic field, it is possible to generate an electrical current.
Drift velocity is the speed with which arbitrarily moving electrons move inside a conductor in the absence of electric potential.
Constant current: When the field is uniform, and its magnitude and direction are constant inside the conductor.
Variable current is the one created by an electric field that varies with time.
Alternating current: The electric field direction is reversed periodically at intervals of time.