4.2 Energy, Power And Resistance Flashcards
What is a diode?
A component that allows current through in one direction only. In the current direction, diodes have a threshold voltage ( typically 0.6V ) above which current can flow.
What is electromotive force (E.m.f) ?
The energy supplied by a source per unit charge passing through the source, measured in volts
What is a filmament lamp?
A bulb consisting of a metal filament that heats up and glows to produce light. As the filament increases in temperature, its resistance increases since the metal ions vibrate more and make it harder for the charge carriers to flow.
What are I-V characteristics?
Plots of current against voltage that show how different components behave.
What is kilowatt-hour?
A unit of electrical energy. It is usually used to measure domestic power consumption.
What is a light dependant resistor?
A light sensitive semiconductor whose resistance increases when light intensity decreases.
What is a negative temperature coefficient thermistors
A temperature sensitive semiconductor whose resistance increases as temperature decreases.
What is an ohm?
The unit of resistance.
What is an ohmic conductor?
A conductor for which the current flow is directly proportional to the potential difference across it, when under constant temperature.
What is ohms law?
The current and potential difference tehohvh an ohmic conductor held under constant physical conditions like temperature are directly proportional, with the constant of proportionality being resistance.
What is potential difference?
The difference of electrical potential between two points on a circuit.
It is also the work done per coulomb to move a charge from the lower potential point to the high potential point.
It is measured in volts
What is power?
The rate of energy transfer on a circuit. It can be calculated as the product of the current and the potential difference between two points.
Measured in watts.
What is resistance?
A measure of how difficult is it for current to flow through a matieral
What is resistivity?
A measure of how difficult it is for charge to travel through a matieral.
It’s is proportional to the objects resistance and cross sectional area and inversely proportional to the objects length.
It is measured in ohm metres
What is a resistor?
A device that has a fixed resistance and follows ohms law.
