Case 1
- Voltage across the plates
- 12V
- Gap between the plates
- 0.01m
1,200.000V/m
Open with these valuesElectric Field Calculator
1,200.000V/m
Result: 1,200.000 V/mBetween two parallel plates the field is the voltage divided by the gap: 12 V across 1 cm is 1200 V/m. Enter the gap in metres — a millimetre is 0.001. Volts per metre and newtons per coulomb are the same unit written two ways.
Worked examples
Case 2
- Voltage across the plates
- 230V
- Gap between the plates
- 0.05m
4,600.000V/m
Open with these valuesCase 3
- Voltage across the plates
- 1.5V
- Gap between the plates
- 0.002m
750.000V/m
Open with these valuesHow it's calculated
E = V ÷ d
- StepEnter the voltage held across the two plates.
- StepEnter the gap in metres — 1 cm is 0.01, 1 mm is 0.001.
- ResultRead the field strength in volts per metre.
Reference table
| Voltage, gap | What it is | Field |
|---|---|---|
| 1.5, 0.002 | An AA cell across a 2 mm gap | 750 |
| 9, 0.003 | A 9 V block across 3 mm | 3000 |
| 12, 0.01 | 12 V across one centimetre | 1200 |
| 100, 0.25 | 100 V, but a quarter of a metre apart | 400 |
| 230, 0.05 | Mains voltage across 5 cm | 4600 |
| 5000, 0.1 | 5 kV across 10 cm | 50000 |
Questions
How do I calculate the field between two plates?
Divide the voltage across the plates by the distance between them: E = V ÷ d. Volts and metres give volts per metre, so 12 V across a 0.01 m gap is 1200 V/m.
What is an electric field?
It is the force a positive unit charge would feel at a point in space. Between two flat parallel plates held at a fixed voltage the field is uniform — the same strength everywhere except near the edges.
What units does field strength use?
Volts per metre, which is identical to newtons per coulomb. Enter volts and metres and no conversion is needed; millimetres and centimetres must be turned into metres first.
What happens if I move the plates closer?
At a fixed voltage the field is inversely proportional to the gap. Halving the gap doubles the field, which is why thin capacitor gaps produce very strong fields from modest voltages.
Does this work for a point charge?
No. E = V ÷ d describes the uniform field between parallel plates only. The field around a point charge falls off with the square of the distance and follows Coulomb's law instead.
Sources and last check
Information, not professional advice.