Watt Calculator
Calculate electrical power, voltage, current, and resistance using Ohm's Law and Watt's Law
Calculate Electrical Parameters
Electric potential difference
Electric current flow
Electrical Parameters Results
Formula used: P = V × I, R = V ÷ I
Input mode: Voltage & Current
Example Calculations
Example 1: 60W Light Bulb
Given: Power = 60W, Voltage = 120V
Current: I = P ÷ V = 60W ÷ 120V = 0.5A
Resistance: R = V² ÷ P = 120² ÷ 60 = 240Ω
Application: Household incandescent bulb
Example 2: Resistor Circuit
Given: Voltage = 4V, Resistance = 8Ω
Current: I = V ÷ R = 4V ÷ 8Ω = 0.5A
Power: P = V² ÷ R = 4² ÷ 8 = 2W
Application: Electronic circuit design
Example 3: Electric Heater
Given: Power = 1500W, Voltage = 120V
Current: I = P ÷ V = 1500W ÷ 120V = 12.5A
BTU Output: 1500W × 3.412 = 5118 BTU/h
Daily Energy: 1500W × 24h = 36 kWh
Essential Formulas
Power Unit Conversions
Common Applications
Understanding Electrical Power and Watt's Law
What is a Watt?
A watt (W) is the SI unit of power, measuring the rate of energy transfer. In electrical circuits, one watt represents the power when one ampere of current flows through a conductor with a potential difference of one volt.
Fundamental Laws
- •Watt's Law: P = V × I (Power = Voltage × Current)
- •Ohm's Law: V = I × R (Voltage = Current × Resistance)
- •Combined: P = I²R or P = V²/R
Practical Applications
Energy Consumption
- • Calculate electricity bills (kWh = kW × hours)
- • Size electrical components and circuits
- • Determine energy efficiency
- • Plan solar panel systems
Circuit Design
- • Calculate heat dissipation in resistors
- • Select appropriate wire gauges
- • Design power supplies
- • Analyze motor requirements
Key Electrical Relationships
Power Calculations
- • P = V × I (basic power law)
- • P = I² × R (current squared times resistance)
- • P = V² ÷ R (voltage squared divided by resistance)
Safety Considerations
- • Higher power = more heat generation
- • Component power ratings must not be exceeded
- • Proper cooling required for high-power devices
- • Circuit protection (fuses, breakers) essential