Electric cells

Understandings:

• Cells
• Internal resistance
• Secondary cells
• Terminal potential difference
• Electromotive force (emf)

Applications and skills:

• Investigating practical electric cells (both primary and secondary)
• Describing the discharge characteristic of a simple cell (variation of terminal potential difference with time)
• Identifying the direction of current flow required to recharge a cell
• Determining internal resistance experimentally
• Solving problems involving emf, internal resistance and other electrical quantities

Guidance:

• Students should recognize that the terminal potential difference of a typical practical electric cell loses its initial value quickly, has a stable and constant value for most of its lifetime, followed by a rapid decrease to zero as the cell discharges completely