Ohm's Law Calculator
Physics Class 12 - V = IR
Voltage (V) =
12.00
V = 12V | I = 2A | R = 6Ω
Ohm's Law Triangle
V = I × R
I = V / R
R = V / I
V (Voltage)
Volts (V)
Electrical pressure
I (Current)
Amperes (A)
Flow of electrons
R (Resistance)
Ohms (Ω)
Opposition to flow
Applications
- Circuit Design: Calculate resistor values for LED circuits
- Power: P = VI = I²R = V²/R
- Safety: Determine wire gauge for current capacity
- Electronics: Design voltage dividers, current limiting
Power Formulas
P = V × I
P = I² × R
P = V² / R
Where P is power measured in Watts (W)
Series and Parallel Circuits
Series Circuit:
R_total = R₁ + R₂ + R₃ + ...
Same current flows through all components
Parallel Circuit:
1/R_total = 1/R₁ + 1/R₂ + 1/R₃ + ...
Same voltage across all components
Kirchhoff's Laws
Kirchhoff's Current Law (KCL):
Sum of currents entering = Sum of currents leaving
Kirchhoff's Voltage Law (KVL):
Sum of voltage drops = Sum of voltage sources in a loop
Solved Examples
Example 1: Find current through a 12V battery connected to a 6Ω resistor.
I = V/R = 12/6 = 2A
Answer: I = 2 Amperes
Example 2: Find power dissipated by the resistor.
P = V × I = 12 × 2 = 24W
Answer: P = 24 Watts
Example 3: Three 10Ω resistors in series. Find total resistance.
R_total = 10 + 10 + 10 = 30Ω
Answer: R = 30 Ohms
Common Units
Voltage
Volt (V) = Joule/Coulomb
Current
Ampere (A) = Coulomb/second
Resistance
Ohm (Ω) = Volt/Ampere
Power
Watt (W) = Joule/second