Flashcards in Modules 4 Definitions Deck (71)
A material that allows the flow of electrical charge. Good conductors
have a larger amount of free charge carriers to carry a current.
Conservation of charge
The total charge in a system cannot change
The flow from positive to negative, used to describe the
direction of current in a circuit.
The unit of charge.
The rate of flow of charge in a circuit.
Substances that contain ions that when dissolved in a solution, act
as charge carriers and allow current to flow.
The opposite direction to conventional current flow. Electrons flow
from negative to positive.
The smallest possible charge, equal to the charge of an
A material that has no free charge carriers and so doesn’t allow the
flow of electrical charge.
Kirchhoff's First Law
A consequence of the conservation of charge. The total
current entering a junction must equal the total current leaving it.
Mean Drift Velocity
The average velocity of an electron passing through an
object. It is proportional to the current, and inversely proportional to the number of
charge carriers and the cross-sectional area of the object.
Quantisation of Charge
The idea that charge can only exist in discrete packets
of multiples of the elementary charge.
A material that has the ability to change its number of charge
carriers, and so its ability to conduct electricity. Light dependent resistors and
thermistors are both examples.
A component that allows current through in one direction only. In the
correct direction, diodes have a threshold voltage (typically 0.6 V) above which
current can flow.
The energy supplied by a source per unit charge passing
through the source, measured in volts.
A bulb consisting of a metal filament, that heats up and glows to
produce light. As the filament increases in temperature, its resistance increases
since the metal ions vibrate more and make it harder for the charge carriers to
Plots of current against voltage, that show how different
A unit of electrical energy. It is usually used to measure domestic
A light sensitive semiconductor whose resistance
increases when light intensity decreases.
The unit of resistance.
A conductor for which the current flow is directly proportional
to the potential difference across it, when under constant physical conditions.
The current and potential difference through an ohmic conductor
held under constant physical conditions are directly proportional, with the constant
of proportionality being resistance.
The difference in electrical potential between two points in a
circuit. It is also the work done per coulomb to move a charge from the lower
potential point to the higher potential point. It is measured in Volts.
The rate of energy transfer in a circuit. It can be calculated as the product
of the current and the potential difference between two points. It is measured in
A measure of how difficult it is for current to flow through a material.
A measure of how difficult it is for charge to travel through a material.
It is proportional to the object’s resistance and cross-sectional area, and inversely
proportional to the object’s length. It is measured in Ohm metres.
A device that has a fixed resistance and follows Ohm’s law.
The unit of potential difference.
Conservation of Energy
Energy cannot be created or destroyed - it can only be transferred into different forms.