Energy, Power and Resistance Flashcards
In the circuit symbol for a cell, which terminal is positive?
The longer terminal.
What is potential difference?
A measure of the transfer of energy by charge carriers.
What is one volt?
The potential difference across a component when when 1J of energy is transferred by 1C of charge passing through the component.
What is the circuit component used to measure potential difference and how is it placed in a circuit?
A voltmeter, which is placed in parallel.
What would be the resistance of the ideal voltmeter?
Infinite resistance, so that no current can flow through it.
What is EMF?
The energy gained by charge carriers, e.g. from a cell.
How do you convert from Joules to Electron Volts?
Divide by e, the charge on an electron.
When an electron is being accelerated by a potential difference, what equation can be used to work out its velocity?
eV = 0.5mv^2
What is one ohm?
The resistance of a component when a PD of 1V is produced per 1A of current.
What is Ohm’s law?
For a circuit component at constant temperature, the current in the wire is directly proportional to the PD across the component.
What is a diode?
A circuit component that only allows current to flow in one direction.
What is resistivity?
A property specific to a certain material that describes its ability to conduct electricity.
What is the relationship between resistance and length of a wire?
Resistance is directly proportional to length.
What is the relationship between resistance and cross-sectional area of a wire.
Resistance is inversely proportional to cross-sectional area.
What is the relationship between temperature and resistance in a thermistor?
As the temperature increases, the resistance decreases.
