Electricity and Magnetism Definitions Flashcards
Conductors
materials that let electrons pass through them
Insulators
materials that hardly conduct(let electrons pass through) at all
Semi-conductors
materials that are poor conductors when cold but better conductors when warm
Earthing
the process of connecting an electrical device to the ground(so that unwanted charge goes away)
Induced magnetism
a term used to describe the process in which a material can be turned into a magnet when it is put inside the magnetic field of any magnet
Current
the amount of charge passing a point in a circuit every second
Potential difference(voltage)
the energy transferred per coulomb of charge
Resistance
opposition to current
Resistors
electrical components that limit the passage of electrical current(provide resistance)
Variable resistor(rheostats)
A resistor whose resistance can be changed manually
Thermistors
resistors that have a high resistance when cold but a much lower resistance when hot(contain semiconductor materials)
Light-dependent resistors(LDRs)
resistors that have a high resistance in the dark but a low resistance in the light
Diodes
resistors that have an extremely high resistance in one direction but a low resistance in the other(allowing current to flow in one direction only)
Power
the rate at which energy is transformed
Alternating current
an electrical current that reverses its direction(many times a second) at regular intervals
Direct current
an electrical current that flows in one direction only
Magnetic field
a region in which a magnetic pole experiences a force
Electric field
a region in which an electric charge experiences a force
Electromotive force(e.m.f.)
the electrical work done by a source in moving a unit charge around a complete circuit
Magnetic material
a material that can be magnetized and is attracted to magnets
Hard magnetic materials
magnetic materials that are difficult to magnetize but do not readily lose their magnetism
Soft magnetic materials
magnetic materials that are relatively easy to magnetize but are only magnetized temporarily
Solenoid
a cylindrical coil of wire that acts as a magnet when carrying electrical current
Magnetic relay
a switch operated by an electromagnet
Circuit breaker
an automatic switch which cuts of the current in a circuit if it rises above a specific value
Transformer
a device which increases or decreases the a.c. voltage of a power source
Step-up transformer
a device which increases the potential difference of a power source
Step-down transformer
a device which decreases the potential difference of a power source
