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EMF and Potential Difference. Animation of current flow. Potential Difference. EMF 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 in a circuit?.
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EMF and Potential Difference Animation of current flow
Potential Difference • EMF • 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 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.
EMF • The EMF of an electrical source is the work done by the source in driving a unitcharge 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 between cell and battery? • When 2 or more cells are connected, a battery is formed.
EMF for cells in series and parallel • What 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 Difference • The p.d. across an electrical component is the work done to drive a unit charge through the component. • V = W / Q V is in volts (V) W is in Joules (J) Q is in Coulombs (C) 1 V = 1 J/C
Measuring P.d. • To measure the potential difference across an electrical component, the voltmeter is connected in parallel to it.
EMF and P.D. • The EMF of the circuit is the sum of the p.d. across all the components in the circuit.