Electrical Systems - Definitions - Level 3 Flashcards
Alternating current (A.C.)
An electric current that first moves in one direction, then moves in the opposite direction with a regular frequency.
Ammeter
A device that measures current when connected in series in a circuit.
Capacitance
The amount of charge a capacitor can store when connected across a potential difference of 1 volt (larger capacitance means capacitor can store more charge for each volt).
Capacitor
A device that can store electric charge (and energy) and then release it at some later time, being made from two parallel oppositely charged plates.
Charging
When a capacitor gains a charge, causing a potential difference across its plates.
Conductors
Materials that allow electric charges to flow through them easily.
Conventional current
Current flowing from the positive to negative terminal of a cell.
Electric current and size
The flow of electricity through a conductor.
The size of a current is the amount of charge flowing per second past a point.
Current Electricity
The continuous flow of electrons through a conductor.
Dielectric constant (Ɛr)
The proportion by which the capacitance increases when a dielectric insulator is placed between the plates of a capacitor.
Direct current (D.C.)
An electrical current that always moves in one direction.
Discharging
When a capacitor loses a charge causing a potential difference across its plates.
Electric current
The flow of electric charge.
Electric field
The field around charged particles that exerts a force on other charged particles.
Electric field lines
A map of an electric field representing the direction of the force that a positive charge would experience.
Electric flux
The product of a surface area and the component of the electric field perpendicular to the surface.
Electric generator
A mechanical device that uses wire loops rotating inside a magnetic field to generate electricity.
Electric potential
The difference in electrical charge between two points in a circuit, (potential difference).
Electric potential energy
The potential energy of a charge due to the position of the charge near other charges.
Electrical energy
A form of energy from electromagnetic interactions.
Electrical force
A fundamental force that results from the interaction of electrical charge.
Electrical insulators
Materials that obstruct the flow of electrical current.
Electrical resistance
The property of opposing electric current.
Electromagnet
A magnet formed by a solenoid that can be turned on and off by turning the current on and off.
Electromagnetic force
The force of attraction or repulsion between two charged particles (one of the four fundamental forces).
Electromagnetic induction
Mechanical energy is converted to electrical energy by moving a loop of wire in a magnetic field or by changing the magnetic field. This results in an induced voltage which can cause a current if the circuit is complete.
EMF (ℰ)
The potential difference across the terminals of a cell when no current is flowing from it.
Electron current
Opposite to conventional current; electron current flows from the negative terminal to the positive terminal.
Faraday’s law of mutual induction
The rate of change in magnetic flux in a coil is directly proportional to the induced voltage.
Impedance
Combination of resistance and reactance in an AC circuit.