Ohm's Law Calculator
Professional electrical engineering calculator for voltage, current, resistance, and power analysis. Supports DC circuits, AC circuits, three-phase systems with comprehensive safety analysis.
Ohm's Law Calculator
Professional electrical calculator for voltage, current, resistance, and power analysis
Circuit Type
⚡
DC Circuit
Direct Current - constant voltage and currentApplications
Electrical Parameters
V
Electric potential difference
A
Electric current flow
Ω
Opposition to current
W
Electrical power
Calculate & Analyze
Circuit Summary
Characteristics:
Constant voltage
Constant current
Simple calculations
Electrical Formulas
Essential electrical engineering formulas for circuit analysis and design calculations.
V = I × R
Common Applications:
P = V × I = I² × R = V² / R
Common Applications:
P = V × I × cos(φ)
Common Applications:
P = √3 × VL × IL × cos(φ)
Common Applications:
Circuit Types
Understanding different electrical circuit configurations and their applications.
Characteristics:
Constant voltage
Constant current
Simple calculations
No frequency considerations
Applications:
Key Formulas:
V = I × R
P = V × I
Energy = P × t
Characteristics:
Sinusoidal waveforms
In-phase voltage and current
Power factor = 1
No energy storage
Applications:
Key Formulas:
V = I × R
P = V × I
RMS values used
Characteristics:
Phase differences
Reactive power
Power factor < 1
Energy storage elements
Applications:
Key Formulas:
S = V × I
P = S × cos(φ)
Q = S × sin(φ)
Characteristics:
Three sinusoidal waveforms
120° phase separation
Constant instantaneous power
Balanced loads
Applications:
Key Formulas:
P = √3 × VL × IL × cos(φ)
S = √3 × VL × IL
Electrical Safety Guidelines
Critical safety information for electrical work. Always prioritize safety and follow proper procedures.
Voltage Safety
Extra Low Voltage (≤50V): Generally safe for direct contact
Low Voltage (50-1000V): Standard electrical safety required
Medium Voltage (1-35kV): Qualified personnel only
High Voltage (>35kV): Expert technicians with specialized equipment
Current Safety
1mA: Threshold of perception for humans
5mA: Maximum safe current for continuous contact
10-20mA: Muscular control lost, cannot let go
50mA: Ventricular fibrillation possible
>100mA: Severe burns and cardiac arrest
Power Safety
Low Power (<100W): Minimal safety concerns
Medium Power (100-1000W): Heat management required
High Power (1-10kW): Professional installation needed
Industrial Power (>10kW): Specialized safety protocols
General Safety
Always de-energize circuits before working
Use proper personal protective equipment (PPE)
Follow lockout/tagout (LOTO) procedures
Test circuits with appropriate instruments
Follow local electrical codes and standards
Electrical Standards
International and regional electrical standards, voltage systems, and safety requirements.
| Region | Standards | Voltages | Frequency |
|---|---|---|---|
International | IEC 60038 - Standard Voltages IEC 60364 - Electrical Installations | 230V/400V (3-phase) 120V/208V 480V/277V | 50Hz/60Hz |
United States | NEC (National Electrical Code) IEEE Standards | 120V/240V (residential) 208V/120V (commercial) 480V/277V (industrial) | 60Hz |
Europe | EN Standards VDE (Germany) | 230V/400V (standard) 110V (construction) 690V (industrial) | 50Hz |
Asia Pacific | AS/NZS (Australia/NZ) JIS (Japan) | 230V/400V (most) 100V/200V (Japan) 220V/380V (China) | 50Hz/60Hz |
Practical Applications
Real-world examples and calculations for common electrical engineering scenarios.
Calculating circuit breaker requirements
For a 1500W heater on 120V: I = P/V = 1500W/120V = 12.5A, use 15A breaker
Determining wire gauge requirements
For 20A circuit: Use 12 AWG copper wire (rated for 20A continuous)
Power consumption analysis
LED bulb 10W vs incandescent 60W: 6x less energy consumption
Motor starting current calculation
5HP motor at 480V: Running current ≈ 6.5A, Starting current ≈ 39A (6x FLA)
Power factor correction
Motor with 0.8 PF: Reactive power = P × tan(cos⁻¹(0.8)) = 0.75 × P
Efficiency calculations
90% efficient motor: Input power = Output power / 0.9
LED current limiting resistor
For 3V LED with 20mA: R = (Vsupply - VLED) / I = (12V - 3V) / 0.02A = 450Ω
Power dissipation in resistors
In 100Ω resistor with 1A: P = I²R = 1² × 100 = 100W
Voltage divider calculations
For 12V input with R1=1kΩ, R2=2kΩ: Vout = 12V × (2kΩ/(1kΩ+2kΩ)) = 8V
Calculator Features
Voltage Analysis
Calculate voltage drops, potential differences, and voltage requirements for any circuit configuration.
Current Calculations
Determine current flow, ampacity requirements, and current ratings for electrical components.
Resistance Analysis
Calculate resistance values, impedance, and load requirements for optimal circuit design.
Power Analysis
Compute active, reactive, and apparent power with efficiency and power factor analysis.
Safety Analysis
Comprehensive safety evaluation with voltage classification and protection requirements.
Circuit Types
Support for DC, AC resistive, AC reactive, and three-phase circuit configurations.
Advanced Analysis
Power factor calculations, efficiency analysis, and engineering recommendations.
Educational Content
Comprehensive electrical engineering education with formulas, examples, and standards.