EMF and Potential EMF and Potential DifferenceDifference

Animation of current flow

Potential DifferencePotential DifferenceEMF

Current will flow between 2 points if there is a potential difference (p.d.) between the 2 points.

The p.d. is provided by the electrical energy source.

What cause a current to flow What cause a current to flow in a circuit?in a circuit?Energy from an electrical energy

source (e.g. cell, battery) will give energy to charges to enable them to flow.

Electrons are given electrical energy by the cell to flow through the circuit. They will use the energy to move across the electrical components in the circuit.

EMFEMFThe EMF of an electrical source is

the work done by the source in driving a unit charge around a complete circuit.

V = W / Q V is in volts (V)W is in Joules (J)Q is in Coulombs (C)

1 V = 1 J/C

What is the difference What is the difference between cell and battery?between cell and battery?When 2 or more cells are

connected, a battery is formed.

EMF for cells in series and EMF for cells in series and parallelparallelWhat are the advantages of

connecting cells in series and parallel?What is the combined EMF in each

case?Refer to text page 301

Cells in parallel Cells in series

Potential DifferencePotential DifferenceThe p.d. across an electrical

component is the work done to drive a unit charge through the component.

V = W / QV is in volts (V)W is in Joules (J)Q is in Coulombs (C)

1 V = 1 J/C

Measuring P.d. Measuring P.d. To measure the potential

difference across an electrical component, the voltmeter is connected in parallel to it.

EMF and P.D. EMF and P.D. The EMF of the circuit is the sum

of the p.d. across all the components in the circuit.