Electrical Resistance Calculator – Ohm's Law
Calculate electrical resistance using voltage and current
Table of Contents
How to Use
- Enter the voltage (V) across the component in volts
- Enter the current (I) through the component in amperes
- Click calculate to see the resistance and power
- The calculator uses Ohm's Law: R = V / I
What is Electrical Resistance?
Electrical resistance is the opposition to the flow of electric current in a conductor. It is measured in ohms (Ω) and determines how much current will flow for a given voltage according to Ohm's Law.
Resistance depends on the material's properties, length, cross-sectional area, and temperature. Good conductors like copper have low resistance, while insulators have very high resistance.
Ohm's Law
Ohm's Law states that resistance equals voltage divided by current:
- R = V / I
- Where R is resistance in ohms (Ω)
- V is voltage in volts (V)
- I is current in amperes (A)
This calculator also determines power dissipation using P = V × I, which shows how much electrical energy is converted to heat.
Common Applications
- Circuit design and component selection
- Determining resistor values needed for specific circuits
- Calculating heat dissipation in components
- Troubleshooting electrical systems
- Power supply design and analysis
- LED current limiting resistor calculations
Frequently Asked Questions
- What is the formula for calculating resistance?
- Resistance is calculated using Ohm's Law: R = V / I, where R is resistance in ohms, V is voltage in volts, and I is current in amperes.
- What does the power calculation tell me?
- The power calculation (P = V × I) shows how much electrical energy is being dissipated as heat. This is important for selecting components that can handle the power without overheating.
- Why is resistance important in circuit design?
- Resistance controls current flow, protects components from excessive current, divides voltage, and converts electrical energy to heat when needed. Proper resistance values are essential for safe and efficient circuit operation.
- What factors affect electrical resistance?
- Resistance is affected by the material type, conductor length (longer = higher resistance), cross-sectional area (larger = lower resistance), and temperature (higher temperature usually increases resistance).
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