Electricity Flashcards
What is a superconductor
A component with 0 resistivity when its temperature falls below its critical temperature
What does a superconductor do
Doesn’t heat up or release any energy when current passes through as there is no resistance
3 Uses of Superconductors
Ultra-fast circuits Ultra-efficient power cables - don’t waste any energy Extremely strong electromagnets - don’t need a power source
What is Emf
Energy transferred to electrical energy per coulomb of charge
What is Potential Difference
Energy transferred from electrical energy per coulomb of charge
What is Current
Charge per second that flows past a point in a circuit
What is Kerchhoff’s 1st Law
The principal of conservation of energy as applied to electrical circuits In any loop in a circuit, the total Emf is equal to the total p.d around the loop
What is Kerchhoff’s 2nd Law
The principal of conservation of charge as applied to a circuit The total current entering any point in a circuit is the same as the total current leaving the same point
What is total resistance in a series circuit
Sum of all resistances
What is total resistance in a Parallel Circuit
1/R(T) = 1/R(1) = 1/R(2)
What is a semiconductor
A component by which resistance and energy supplied to it are inversely proportional Increasing temp. / light will decrease resistance
How do Semiconductors work
Materials initially don’t have many available charge carriers. A more energy is supplied, more charge carriers are released As electrons have more energy to become delocalised
How is temperature deduced from an I/V graph of a thermistor
The higher the gradient, the lower the resistance. Lower resistance means a higher temperature
What is a diode
Semiconductor that only lets current flow in 1 direction and above the threshold voltage of 0.6V
What is Forward Bias
The direction in a diode that current can flow In the opposite direction, resistance is extremely high, so voltage is extremely low
What is Forward Bias
The direction in a diode that current can flow In the opposite direction, resistance is extremely high, so voltage is extremely low
What is a potential divider used for
To supply a constant/variable potential difference from a power supply By using the resistance of a resistor to change the potential difference across a component
What is the relationship between potential difference and resistance in a potential divider
The ratio of pd’s across each resistor is equal to the resistance ratio of the 2 resistors AND The ratio of the p.d across a component to the emf is equal to the ratio of its resistance to the total resistance
I/V Graph for a Filament Lamp
Graph for a Thermistor
Graph for a Diode
What is lost volts
Energy wasted by the cell per coulomb of charge due to internal resistance
How to measure the emf of a battery
Measuring the voltage across a cell using a voltmeter when there is no current running through the cell
Define Resistivity
The product of resistance and cross-sectional area, divided by the length of the material.
Give 4 examples of semiconductors
Semiconductor diodes
Any metal conductors
LDR
Thermistor
How may a thermistor be used as a temperature sensor
An event can be triggered once the temperature drops below a certain value which causes resistance to reach a certain value
