ELECTRIC AND DIRECT CURRENT CIRCUIT :
ELECTROMOTIVE FORCE (EMF)
Maximum potential difference between the two electrodes of the cekk when no current is drawn from the cell
It is independent of the resistance of the circuit
The term 'emf' is used only for the source of emf
it is greater than the potential difference between any two points in a circuit
POTENTIAL DIFFERENCE
P.D is the difference of the potentials between any two points in a closed circuit
Its is proportional to the resistance between the given points
It is measured between any two points of the circuit
P.D is greater than emf when the cell is being charged
RESISTORS IN SERIES AND IN PARALLEL
SERIES CONNECTION
Has a single path from the battery, through each circuit element in turn, then back to the battery
The current through each resistor is the same; the voltage depends on the resistance. The sum of the voltage drops across the resistors equals the battery voltage
The equivalent resistance (that single resistance that gives the same current in the circuit)
PARALLEL CONNECTION
Splits the current; the voltage across each resistor is the same
The total current is the sum of the currents across each resistor
This gives the reciprocal of the equivalent resistance
KIRCHHOFF'S LAW
The sum of all the electric potential differences around a loop is zero
Also called Kirchhoff's voltage law or Kirchhoff's second law
Deals with the conservation of charge entering and leaving a junction.
WHEATSTONE BRIDGE
An electrical circuit used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown component.
GALVANOMETER
An electromechanical instrument used for detecting and indicating an electric current.
Works as an actuator, by producing a rotary deflection of a pointer, in response to electric current flowing through a coil in a constant magnetic field
ELECTRIC CURRENT
A complete circuit is one where current can flow all the way around
CURRENT DENSITY
Defined as the current per unit area in a conductor, where A is the cross section of conductor.
A vector quantity
Units: Amps/m^2
Current density J and the electric field E are both established in a conductor as a result of a potential difference across the conductor
CURRENT AND DRIFT VELOCITY