CURRENT ELECTRICITY
➢ This is the flow of electrons through a conductor per unit time.
A push called voltage is needed to enable the charges to flow. The charge move from high potential
energy to low potential energy.
o SI-Unit of current is ampere (A).
Ammeter
➢ This is a device used to measure current.
POTENTIAL DIFFERENT (P.D) AND ELECTROMOTIVE FORCE
POTENTIAL DIFFERENT (P.D)
➢ This is the electrical pressure in a closed circuit
OR
➢ This is the work done per unit charge in a moving electric current from one point to another.
That is:
P.d = Work done (W)
Charge moved (Q)
o The SI-Unit of P.d is volts (V). One volt is equivalent to one joule per coulomb.
o P.d is measured by a device called Voltmeter.
ELECTROMOTIVE FORCE (E.MF)
➢ This is the electrical pressure in an open circuit.
OR
➢ This is the potential difference across the cell terminals where there is no current flowing
through it.
o The SI-Unit of e.m.f is volts (V).
o Em.fis measured by a device called Voltmeter.
1. E.m.f is not a force but a process by which a device such as a cell or generator converts chemical
or mechanical energy into electrical energy. It can be thought of as an electrical potential energy
that is converted into the kinetic energy of the charges moving in an electric circuit.
ELECTRIC CIRCUIT
➢ This is a closed path around which the electric charge moves.
CIRCUIT COMPONENTS
➢ These are electrical device used in a circuit.
VERIFICATION OF OHM’S LAW
❖ An experiment to verify ohm’s law was performed by a scientist called Mr. G.S Ohm
(George.S.ohm).
Apparatus used by him are:-
✓ Rheostat (Rh)
✓ Ammeter (A)
✓ Voltmeter (V)
✓ Switch (K)
✓ Connecting wire
✓ Dry cell
