Potential difference/Voltage [Volts/V] [Voltmeter]- The work done in moving each unit of charge from one point to the other point.
Current [Amperes/A] [Ammeter]- The rate at which electrons flow past a certain point
I [Current] = Q[Total Charges]/T[Time]
Resistance [Ohms] - Opposition to current
Ohms Law = Current is directly proportional to potential difference at a constant temperature
$$ R = V/I $$
Factors Affecting Resistance -
Temperature increases - Increases resistance
REASON - Electrons collide with atoms as they pass, electrons lose energy, atoms gain energy, atoms vibrate faster, increased temperature [greater average KE]
Material
Longer Wire → More Resistance [More collisions due to length]
Thicker Wire → Lesser Resistance [More space for electrons and hence more can flow]
$$ (Resistance.Area)/Length = (Resistance.Area)/Length $$