12 V across 470 Ω
- Input
- V = 12 V, R = 470 Ω → I, P
- Expected output
- 25.53 mA e 0.3064 W
12 ÷ 470 and 12² ÷ 470.
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ohms law calculator
The Ohm's law tab opens with two fields filled in. Change a field, or fill in another two, and the remaining results appear with the formula for each. It accepts 4k7, 2m and 100n.
12 ÷ 470 and 12² ÷ 470.
220 ÷ 8.8 and 220² ÷ 8.8.
5 × 10 and 5² × 10.
√(40 × 10) and √(40 ÷ 10).
12 ÷ 2 and 12 × 2.
0.45 ÷ 9 and 9² ÷ 0.45.
At 220 V, 25 A (5,500 ÷ 220). At 127 V, 43.3 A (5,500 ÷ 127). A heater element is a pure resistance, so the power factor is 1. That figure is the appliance current: it does not say which breaker or wire to use, which is a job for a licensed electrician.
V = I × R: voltage equals current times resistance.
I = V ÷ R. With 12 V and 470 Ω, that is 25.5 mA.
P = V × I, which combined with V = I × R gives P = I² × R and P = V² ÷ R.
Use the voltage that reaches the appliance: line-to-neutral (120 V) or across two lines (240 V). Line-to-line in a three-phase system, 120 V line-to-neutral becomes about 381.1 V.
Typical nameplate powers, only as a starting point. Every model differs: the label on your appliance rules. Edit the value freely.
I = 5,500 ÷ (220 × 1) = 25 A
Running for 1 hour it uses 5.5 kWh.
| Appliance | W | A @ 120 V | A @ 240 V |
|---|---|---|---|
| 5500 | 45.83 | 22.92 | |
| 7500 | 62.5 | 31.25 | |
| 4500 | 37.5 | 18.75 | |
| 1000 | 8.333 | 4.167 | |
| 1300 | 10.83 | 5.417 | |
| 1900 | 15.83 | 7.917 | |
| 1400 | 11.67 | 5.833 | |
| 1500 | 12.5 | 6.25 | |
| 2000 | 16.67 | 8.333 | |
| 1800 | 15 | 7.5 | |
| 1200 | 10 | 5 | |
| 200 | 1.667 | 0.8333 | |
| 9 | 0.075 | 0.0375 |
Current of each appliance at 120 V and 240 V with cosφ 1 (the field above). Motors and compressors often have cosφ below 1: change the field to see the effect.
Limit of this tool. It shows the current and powers implied by the load you enter. It does not size a breaker or a cable: that depends on installation method, length, circuit grouping and temperature, and belongs to a licensed electrician or engineer following your local code.