Electricity Flashcards
What is an ammeter?
A device that measures the current in the loop of the circuit that it is connected in series with. An ideal ammeter is modelled to have zero resistance
What is current?
The rate of flow of charge in a circuit
What is the Electromotive force?
The amount of energy transferred by a source to each unit of charge that passes through it
What is meant by internal resistance?
The resistance to the flow of charge within a source. Internal resistance results in energy being dissipated within the source
What is a light dependant resistor?
A light sensitive semiconductor whose resistance increases when the process light intensity decreases
What is an ohmic conductor?
A conductor for which the current flow is directly proportional to the potential difference across it, when under constant physical conditions
What is Ohms 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
What are parallel circuits?
Components are connected in parallel when they are connected across each other ( in separate loops )
What is a potential divider?
A method of splitting a potential difference, by connecting two (or more) resistors in series. The total potential difference is split in the ratio of their resistances
Define resistance
A measure of how difficult it is for current to flow through a material
Define resistivity
A quantity that is proportional to an objects resistance and cross sectional area, and inversely proportional to the objects length
What happens to the pd, resistance, and current through the resistor when resistors are connected in series?
The pd is split in the ratio of their resistances.
The total resistance is equal to the sum of the resistances of the resistors.
The current through resistors in series is identical for each resistor
What happens to the pd, resistance, and current through the resistor when resistors are connected in parallel?
The pd across resistors connected in parallel is identical for each resistor.
The total resistance is equal to the inverse of the sum of the inverses of the resistances of the resistors.
The current is split between the resistors
What are series circuits?
Circuits where components are connected in one loop
What is a superconductor? What are some uses of them?
A material that has zero resistivity when the temperature is decreased to, or below, the materials critical temperature.
Superconductors can be used to produce strong magnetic fields and reduce energy loss when transmitting electrical power
Define terminal potential difference
The potential difference across the terminals of a power source. It is equal to the sources emf minus any voltage drop over the sources internal resistance
What is a thermistor?
A temperature sensitive semiconductor whose resistance increases when temperature decreases
What is a voltmeter?
A device used to measure the potential difference across components. An ideal voltmeter is modelled to have infinite resistance
