Topic 12: Electric Current & Topic 13: DC Circuits Flashcards
Electric current
The rate of flow of charge (in the wire or component)
Potential difference
Work done or energy transferred per unit charge between two points when charge moves from one point to another
Resistance
Potential difference/current, a measure of the difficulty of making current pass through a component
Ohm’s Law
The pd across a metallic component is proportional to the current, as long as the physical conditions do not change
Ohmic conductor
A conductor that obeys ohm’s law
Semiconductor
A substance in which the number of charge carriers increases when the temperature is raised
Resistivity
Resistance per unit length x area of cross section
Superconductor
A material that has zero electrical resistance/ a wire or device made out of a material that has zero resistivity at and below a critical temperature that depends on the material
Potential divider
Two or more resistors in series connected to a source of pd - can reduce the current through a component and the pd across it to zero
Electromotive force (emf)
The amount of electrical energy per unit charge produced inside a source of electrical energy/
The electrical energy produced per unit charge passing through the source
Charge carriers
Charged particles that move through a substance when a pd is applied across it
Critical temperature of a superconducting material
Temperature at or below which it’s resistivity is zero
Light-dependent resistor (LDR)
Resistor which is designed to have a resistance that changes with light intensity
Positive temperature coefficient
The resistance of a metal increases when its temperature is increased
Negative temperature coefficient
The resistance of a semiconductor decreases when its temperature is increased
