Paper 1: Electricity Flashcards
Define Electric current
The flow of charge per unit time
Q=It
Define potential difference
the energy transferred per unit charge
E = VQ
Define resistance
The measure of how difficult for charge to pass through a component.
V=IR
What carries charge in a circuit?
the negatively charged electrons
What is Ohm’s law?
For an ohmic conductor, current is directly proportional to the potential difference across it when temperature is constant.
Describe how a semiconductor diode is used.
this component will allow current to flow met with the threshold voltage. Otherwise it is very resistive
What is a diode?
A component with has a direction bias. It only allows current o flow in one direction, if inserted backwards, it is very resistive.
Does a filament lamp follow Ohm’s law?
Yes up until a certain point where the component heats up. As current increases, the circuit heats up. So resistance increases as current increases
What is resistivity?
is a measure of how easily a material conducts electricity
Why does resistance increase when the temperature of a metal conductor increases?
The atoms of the metal gain kinetic energy and moves more, which causes the charge carriers (electrons) to collide more frequently, therefore slows them down. So current decreases and resistance increases.
Why do thermistors’ resistance decrease as temperature increases?
Increasing the temperature in a thermistor causes electrons to be emitted from the atoms. Therefore the number of charge carriers increases so as current increases, resistance decreases.
What is a superconductor?
a material at which below the critical temperature has 0 resistivity.
