Question

A cell phone or computer battery has three ratings marked on it: a charge capacity listed in mAh (milliamp-hours), an energy capacity in Wh (watt-hours), and a potential rating in volts. If the charge Q were stored on a parallel-plate capacitor with air as the dielectric, at the potential V , what would be the corresponding capacitance?

Answer 1

The capacitance
`(\(C\))` of a parallel-plate capacitor is determined by the formula:
`\[ C = (Q)/(V) \]`

The capacitance
`(\(C\))` of a parallel-plate capacitor is determined by the formula:
`\[ C = (Q)/(V) \]`

where:

• 
  `\(C\)` is the capacitance,

• 
  `\(Q\)` is the charge stored on the capacitor,

• 
  `\(V\)` is the potential difference (voltage) across the capacitor.

In the context of this particular question, the charge capacity of a cell phone or computer battery is represented by
`\(Q\)` (in mAh), and the potential rating is represented by
`\(V\)` (in volts).

If the charge capacity is given in milliamp-hours (mAh), it may need to be converted to coulombs (C) since
`\(1 \text{ mAh} = 3.6 \text{ C}\)` (1 milliamp-hour is equivalent to 3.6 coulombs).

Once
`\(Q\)` is in coulombs and
`\(V\)` in volts, you can use the formula to find the capacitance
`\(C\)`.