Ohm's Law Calculator

V = I × R | P = V × I

What to Calculate?

Enter Known Values

Voltage

Enter values to calculate

Formula Used

V = I × R

Voltage equals current multiplied by resistance

All Circuit Values

Voltage

Volts (V)

Current

Amperes (A)

Resistance

Ohms (Ω)

Power

Watts (W)

Power Distribution

Values Comparison

Example 1: Finding Voltage

Problem: A circuit has a current of 2A flowing through a resistance of 10Ω. What is the voltage?

Solution:
V = I × R
V = 2A × 10Ω
V = 20V

Example 2: Finding Current

Problem: A 120V battery is connected to a 60Ω resistor. What current flows through the circuit?

Solution:
I = V / R
I = 120V / 60Ω
I = 2A

Example 3: Finding Resistance

Problem: A 9V battery supplies 0.5A to a circuit. What is the resistance?

Solution:
R = V / I
R = 9V / 0.5A
R = 18Ω

Example 4: Finding Power

Problem: A device operates at 120V and draws 5A. What is the power consumption?

Solution:
P = V × I
P = 120V × 5A
P = 600W

Example 5: Light Bulb

Problem: A 100W light bulb is connected to 120V. What is its resistance and current?

Solution:
I = P / V = 100W / 120V = 0.833A
R = V / I = 120V / 0.833A
R = 144Ω, I = 0.833A

Example 6: Car Battery

Problem: A car's 12V system has a headlight with 4Ω resistance. Find current and power.

Solution:
I = V / R = 12V / 4Ω = 3A
P = V × I = 12V × 3A
I = 3A, P = 36W

Understanding Ohm's Law

Ohm's Law is a fundamental principle in electrical engineering that describes the relationship between voltage, current, and resistance in an electrical circuit.

The Three Key Relationships:

V = I × R

Voltage (V) equals Current (I) times Resistance (R)

I = V / R

Current (I) equals Voltage (V) divided by Resistance (R)

R = V / I

Resistance (R) equals Voltage (V) divided by Current (I)

Power Formulas:

P = V × I

Power (P) equals Voltage (V) times Current (I)

P = I² × R

Power equals Current squared times Resistance

P = V² / R

Power equals Voltage squared divided by Resistance

Units of Measurement:

Voltage (V): Measured in Volts (V) - the electrical pressure
Current (I): Measured in Amperes (A) - the flow of electrons
Resistance (R): Measured in Ohms (Ω) - opposition to current flow
Power (P): Measured in Watts (W) - rate of energy consumption

Practical Applications

Home Wiring

Calculate wire sizes and circuit breaker ratings for home electrical systems

Electronics

Design circuits with proper resistor values for LEDs, sensors, and components

Automotive

Diagnose electrical problems and calculate power requirements in vehicles

Solar Power

Size solar panels and batteries for off-grid power systems

Understanding Ohm's Law

Ohm's Law is one of the most fundamental principles in electrical engineering and physics. Discovered by German physicist Georg Simon Ohm in 1827, it describes the mathematical relationship between voltage, current, and resistance in an electrical circuit.

The Three Variables

Ohm's Law involves three key electrical quantities:

Voltage (V): The electrical potential difference that drives current through a circuit, measured in Volts (V)
Current (I): The flow of electric charge through a conductor, measured in Amperes (A)
Resistance (R): The opposition to current flow, measured in Ohms (Ω)

Ohm's Law Formulas

The three forms of Ohm's Law are:

V = I × R - Calculate voltage when current and resistance are known
I = V / R - Calculate current when voltage and resistance are known
R = V / I - Calculate resistance when voltage and current are known

Power Calculations

Electrical power can be calculated using these formulas:

P = V × I - Power equals voltage times current
P = I² × R - Power equals current squared times resistance
P = V² / R - Power equals voltage squared divided by resistance

Using This Calculator

Follow these steps:

Step 1: Select what you want to calculate (Voltage, Current, Resistance, or Power)
Step 2: Enter the two known values
Step 3: Click "Calculate" to see the result
Step 4: View all circuit values in the results section
Step 5: Check the Examples tab for practice problems
Step 6: Learn more in the Guide tab

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