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Voltage Calculator
Find voltage from current and resistance using Ohm's Law.
What is a Voltage Calculator?
A Voltage Calculator finds the electrical potential difference across a part of a circuit using Ohm's Law. It is useful for students, electricians, and hobbyists who work with electrical circuits.
How to Use the Voltage Calculator
- Enter the current (I) in amperes.
- Enter the resistance (R) in ohms.
- Click "Calculate Voltage" to see the result in volts.
Formula Explanation
Voltage (V) = Current (I) × Resistance (R)
This is Ohm's Law, the basic relationship between voltage, current, and resistance. You can rearrange it to find the other values:
| To find | Formula |
|---|---|
| Voltage (V) | V = I × R |
| Current (I) | I = V ÷ R |
| Resistance (R) | R = V ÷ I |
| Power (P) | P = V × I |
Worked Example
A current of 2 A flows through a 12 Ω resistor. Voltage = 2 × 12 = 24 V. If the current is 250 mA, first convert it to amperes (250 mA = 0.25 A) and then multiply: 0.25 × 12 = 3 V.
Practical Uses
Voltage calculations help you design and troubleshoot circuits and choose the right components. They also help you check that devices run within their rated limits.
Electricians and hobbyists use this formula for household wiring, electronics projects, and automotive electrical systems.
Frequently Asked Questions
1. What is Ohm's Law?
Ohm's Law states that voltage equals current multiplied by resistance (V = I × R). It is the basic equation for understanding how electricity behaves in a circuit.
2. What is the difference between voltage and current?
Voltage is the electrical "pressure" that pushes current through a circuit. Current is the flow of electric charge. Voltage causes current to flow, much like water pressure causes water to flow.
3. Can this calculator be used for both AC and DC circuits?
Ohm's Law applies directly to DC circuits and to purely resistive AC circuits. For AC circuits with inductors or capacitors, you need impedance instead of simple resistance.
4. My current is in milliamps (mA). What should I do?
Divide the milliamp value by 1000 to get amperes. For example, 500 mA = 0.5 A. Then enter the value in the current field.