### 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

**Examples**

- If a 40Ah was connected to :
- a lamp drawing 0.2 amps
- It would take:
- \text{0.2A x t = 40Ah }
- Where
**t**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.