Definitions - Electricity Flashcards
Electric charge
The excess amount / number of protons or electrons
Unit of electric charge
Coulomb - 6,25 x 10^18 electrons
Current
The rate of flow of charge. The drift of ‘free’ electrons (those being electrons not strongly attracted to the nucleus temporarily becoming dislodged from the outer shell)
Current Measured
current (symbol, I) is measured in ampere (symbol, A) - using an ammeter connected in series.
Why does charge flow?
Potential Difference
Coulomb
The amount of charge passing a cross-section of a conductor in one second, where the current is one ampere
Electron
charge is -1.6 x 10^-19
Potential difference
work done per unit positive charge
Power
The rate of doing work
work
The rate of flow of current
Ohm’s Law
Current through a conductor is directly proportional to the potential difference across the conductor at constant temperature
Series circuit
- Current is same
- Potential difference is divided
Parallel Circuits
- Sum of current in each branch equals total current
-
Resistance
A materials opposition to the flow of current
e.m.f
Electromotive force - the work done by the source in driving a unit charge around a complete circuit
E = W / Q
