Electricity Flashcards
(17 cards)
What’s an electric current?
rate of flow of charge
negative to positive
measured in amps
define coulomb
one coulomb is the charge which passes a point when a current of 1A flows for 1s
What’s an electrolyte?
A solution which conducts electricity. it contains positive and negative ions.
Ions move in opposite directions when connected to a cell
What are charge carriers?
Any particle with electric charge. Particles which contribute to an electric current
What is the difference between electric current in a metal and an electrolyte?
Electric current is the net flow of charged particles. In a metal, the charge carriers are free/delocalised electrons. In an electrolyte the charge carriers are ions.
Define EMF
The amount of chemical energy converted to electrical energy per coulomb of charge (C) when charge passes through a power supply
Define conventional current
Flow of electrical charge from positive to negative
What is potential difference?
The work done per unit charge between two points
What units are equivalent to the volt?
Joules per Coulomb (JC−1 )
What is the resistance of an ideal voltmeter?
Infinite
What is thermionic emission?
The emission of electrons from the surface of a
heated metal
What is Ohm’s Law?
For a metallic conductor at constant temperature
the p.d. is proportional to current
What is electrical resistance?
The opposition of an object to a flow of current through it.
Why does resistance increases with temperature?
The amplitude of lattice ion vibrations increases
causing more frequent collisions between electrons and lattice ions, leading to the electrons doing more work as they move through the wire.
Why does current flow lead to heating in
components?
Electrons collide with the lattice ions and transfer some of their kinetic energy to the lattice ion’s vibrations.
What is an Ohmic conductor?
An object for which p.d. is proportional to current.
What is meant by the threshold pd of a diode?
The pd at which resistance starts to fall rapidly as pd increases.
