ZIMSEC O Level Combined Science Notes: The Ampere-Hour

  • It is used to measure the current capacity of cells and batteries
  • is the amount of energy charge in a battery/cell that will allow one ampere of current to flow for one hour
  • It is thus a unit of measuring a cell/battery’s charge
  • For example if a battery is rated as 40Ah
  • It means it supplies 40Ah
  • It would mean that it supplies current at
  • 1 ampere for 40 hours or 4 amperes for 10 hours


  • If a 40Ah was connected to :
  • a lamp drawing 0.2 amps
  • It would take:
  • \text{0.2A x t = 40Ah }
  • Where is time in hours
  • \text{t=}\dfrac{40}{0.2}
  • 200 hours
  • If a radio drawing 5 amps was connected instead
  • It would last
  • \text{t=}\dfrac{40}{5}
  • 8 hours

To access more topics go to the Combined Science Notes page.