Ohm's Law Calculator

Basic Ohm's Law

Ohm's Law Formulas:

V = IR (Voltage = Current × Resistance)
I = V/R (Current = Voltage ÷ Resistance)
R = V/I (Resistance = Voltage ÷ Current)

Voltage (V) - Volts:

Current (I) - Amperes:

Resistance (R) - Ohms:

Common Voltage Levels:
AA Battery: 1.5V
Car Battery: 12V
Household (US): 120V
Household (EU): 230V

Safety Notes:
> 50V can be dangerous
Always follow electrical safety

Electrical Power

Power Formulas:

P = VI (Power = Voltage × Current)
P = I²R (Power = Current² × Resistance)
P = V²/R (Power = Voltage² ÷ Resistance)
Energy = P × t (Watt-hours)

Voltage (V) - Volts:

Current (I) - Amperes:

Resistance (R) - Ohms:

Power (P) - Watts:

Time (t) - hours:

Common Power Ratings:
LED Bulb: 5-15W
Laptop: 45-85W
Microwave: 700-1200W
Hair Dryer: 1000-1875W
Electric Heater: 1500W

Energy Cost:
kWh = (Watts × Hours) ÷ 1000

Series Circuit Analysis

Series Circuit Rules:

R_total = R₁ + R₂ + R₃ + ...
I_total = I₁ = I₂ = I₃ (same current)
V_total = V₁ + V₂ + V₃ (voltage divides)

Resistance 1 (R₁) - Ohms:

Resistance 2 (R₂) - Ohms:

Resistance 3 (R₃) - Ohms:

Supply Voltage (V) - Volts:

Series Circuit Properties:
• Same current through all components
• Voltages add up to supply voltage
• Total resistance is sum of all resistances
• If one component fails, circuit breaks

Common Applications:
• Christmas lights (old style)
• Voltage dividers

Parallel Circuit Analysis

Parallel Circuit Rules:

1/R_total = 1/R₁ + 1/R₂ + 1/R₃ + ...
V_total = V₁ = V₂ = V₃ (same voltage)
I_total = I₁ + I₂ + I₃ (current divides)

Resistance 1 (R₁) - Ohms:

Resistance 2 (R₂) - Ohms:

Resistance 3 (R₃) - Ohms:

Supply Voltage (V) - Volts:

Parallel Circuit Properties:
• Same voltage across all components
• Currents add up to total current
• Total resistance less than smallest resistor
• Components work independently

Common Applications:
• Household wiring
• Car electrical systems