Electric circuits definitions Flashcards
Conductors
A material that allows the flow of electrical charge. Good conductors
have a larger amount of free charge carriers to carry a current.
Conventional Current
The flow from positive to negative, used to describe the direction of current in a circuit.
Electric Current
The rate of flow of charge in a circuit.
Electrolytes
Substances that contain ions that when dissolved in a solution, act as charge carriers and allow current to flow.
Electron Flow
The opposite direction to conventional current flow. Electrons flow from negative to positive.
Elementary Charge
The smallest possible charge, equal to the charge of an electron.
Insulators
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.
Semiconductors
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.
Diode
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.
Electromotive Force
The energy supplied by a source per unit charge passing through the source, measured in volts.
Kilowatt-Hour
A unit of electrical energy. It is usually used to measure domestic power consumption
Ohmic Conductor
A conductor for which the current flow is directly proportional to the potential difference across it, when under constant physical conditions.
Ohm’s Law
The current and potential difference through an ohmic conductor held under constant physical conditions are directly proportional, with the constant of proportionality being resistance.
Potential Difference
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.
Power
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 Watts.
Internal Resistance
The resistance to the flow of charge within a source. Internal resistance results in energy being dissipated within the source.
Kirchhoff’s Second Law
A consequence of the conservation of energy. The sum of the voltages in any closed loop must equal zero.
Lost Volts
The difference between a source’s emf and the terminal voltage. It is equal to the potential difference across the source’s internal resistance.
Potential Divider
A method of splitting a potential difference, by connecting two resistors in series. The total potential difference is split in the ratio of their resistances.
Sensor Circuits
A circuit that reacts to external conditions. They commonly involve a semiconductor connected in a potential divider arrangement.
Terminal PD
The potential difference across the terminals of a power source. It is equal to the source’s emf minus any voltage drop over the source’s internal resistance.
