Year 12 - Current Electricity Flashcards
1 Volt
One voltis the potential difference between two points in an electrical circuit, when one joule of electrical energy is transferred, as one coulomb of charge passes between the points or 1 Joule of Work Done per 1 Coulomb of charge.
Ammeter
A measuring device that measures the current. An ideal ammeter has zero resistance. In reality Ammeters have negligible resistance.
Conductivity
The measure of the ease at which an electric charge or heat can pass through a material. It is the reciprocal of Resistivity.
Conventional Current
The rate of flow of charge from the positive to the negative terminal. Note: In a metal the electrons actual flow in the opposite direction.
Critical Temperature
The temperature below which a material becomes superconducting and the resistivity drops to zero.
Diode
An electrical component that is used ina circuit to allow current to flow only in a specific direction. When the conventional current is in the direction of the arrowhead symbol.
Direct Current
An electric current that is in one direction, so the flow of charge is always in the same direction.
Electric Current
The rate of flow of charge or Charge per Unit Time
Electromotive Force (Emf)
Total work (done)/energy (supplied) per unit charge (by battery) moving the charge the whole way round circuit.
Internal Resistance, r
Resistance inside the cell/battery.
Kirchhoff’s First Law
The total/sum of the currents entering a junction is equal to the total/sum of the currents leaving the junction or the sum of the currents at a junction is zero e.g. I1+I2+I3…=0
Kirchhoff’s Second Law
The net electromotive force e.m.f. around a closed loop is equal to the sum of potential drops around the loop e.g. V1+V2+V3…=E
Light Dependant Resistor (LDR)
A light sensitive component. The resistance is inversely proportional to the light intensity.
Multimeter
A measuring device that can measure multiple electrical properties. A typical multimeter can measure potential difference (voltage), resistance, and current. They are normally more precise than a normal ammeter of Voltmeter.
Non-Ohmic
Current is not directly proportional to the Potential Difference (not a straight line, line curves).
Ohmic
Current is directly proportional to the Potential Difference (Straight Line).
Ohm’s Law
The current through a conductor between two points is directly proportional to the potential difference across the two points.
Parallel Circuits
Components are connected in parallel when they are connected in separate branches causing different loops.
Potential Difference (P.D)
Work done per unit charge, between two points in a circuit.
Potential Divider
A potential divider isa simple circuit that uses resistors to supply a variable ‘potential difference’ (i.e. voltage). It produces an output voltage (Vout) that is a fraction of its input voltage (Vin).
Resistance
A measure of how difficult it is for current to flow through a material/substance. The current is inversely proportional to the resistance.
Resistivity
A property that describes the extent to which a material opposes the flow of electric current through it.
Resistors in Parallel
The potential difference across resistors connected in parallel is identical for each resistor. The current is split between the resistors. The total resistance is equal to the inverse of the sum of the inverses of the resistances of the resistors.
Resistors in Series
The current through resistors connected in series is identical for each resistor. The potential difference is split in the ratio of their resistances. The total resistance is equal to the sum of the resistances of the resistors.
Series Circuits
Components are connected in series when they are connected in the same loop.
Superconductor
Resistance is zero at (or below)criticaltemperature.
Terminal P.D.
The potential difference across the terminals of a power source. It is equal to the source’s e.m.f. minus any p.d. drop over the source’s internal resistance.
Thermistor
A temperature sensitive component. The resistance is inversely proportional to the temperature.
Voltmeter
A measuring device used to measure the potential difference (Voltage) across components. An ideal voltmeter has infinite resistance. In Reality a Voltmeter has a resistance in the region of 10MW.
