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Ohm's Law Calculator

Calculate voltage, current, resistance, and power in electrical circuits with interactive visualization

Parameters

Vⓘ
Enter voltage or leave empty to calculate
Aⓘ
This value will be calculated
Ωⓘ
Enter resistance or leave empty to calculate
Show Trail

Controls

xⓘ
Calculating current from voltage and resistance
Animation: Stopped | Time: 0.00s

Calculated Values

Voltage:
12.00;V12.00;V
Current:
0.12;A0.12;A
Resistance:
100.00;Ω100.00;Ω
Power:
1.44;W1.44;W

Examples

Example 1: Basic Circuit

A simple circuit with 12V battery and 100Ω resistor.

  • Current: 0.120.12
  • Power: 1.441.44

Example 2: High Power Circuit

A circuit with 24V and 2Ω resistance for high current.

  • Current: 12.0012.00
  • Power: 288.00288.00

Example 3: Low Power LED Circuit

An LED circuit with 3.3V and 330Ω resistor.

  • Current: 0.010.01
  • Power: 0.030.03

Visualization

Ohm's Law

Ohm's Law is one of the most fundamental principles in electrical engineering and physics, describing the relationship between voltage, current, and resistance in electrical circuits. It states that the current through a conductor between two points is directly proportional to the voltage across the two points.

The mathematical relationship is expressed as V = I × R, where V is voltage in volts, I is current in amperes, and R is resistance in ohms. This simple equation forms the foundation for understanding electrical circuits and is essential for circuit analysis and design.

Ohm's Law applies to linear resistive elements, meaning the resistance remains constant regardless of the applied voltage or current. This is true for most metallic conductors at constant temperature. However, some materials and components (like diodes, transistors, and certain types of resistors) exhibit non-linear behavior.

The law can be rearranged to solve for any of the three variables: I = V/R for current, R = V/I for resistance, and V = I × R for voltage. This flexibility makes it a powerful tool for circuit analysis and troubleshooting.

Power dissipation in a resistor can be calculated using P = V × I, which can be expressed in terms of Ohm's Law as P = I²R or P = V²/R. This relationship is crucial for understanding energy consumption and heat generation in electrical circuits.

Key Concepts

  • Voltage (V): Electrical potential difference, measured in volts (V)
  • Current (I): Flow of electrical charge, measured in amperes (A)
  • Resistance (R): Opposition to current flow, measured in ohms (Ω)
  • Power (P): Rate of energy transfer, measured in watts (W)
  • Linear Relationship: V = I × R for constant resistance
  • Power Equations: P = V × I = I²R = V²/R

Real-World Applications

  • Circuit Design: Calculating component values and power ratings
  • Troubleshooting: Diagnosing electrical problems in circuits
  • Power Systems: Understanding voltage drops and current flow
  • Electronics: Designing amplifiers, filters, and other circuits
  • Safety: Ensuring proper component ratings and wire sizing

Physics Equations

Ohm's Law:
V=I×RV = I \times R
Current:
I=VRI = \frac{V}{R}
Resistance:
R=VIR = \frac{V}{I}
Power:
P=V×I=I2R=V2RP = V \times I = I^2R = \frac{V^2}{R}

Step-by-Step Solution

See how the main results are calculated.

1

Step 1: Identify Known Values

List the given values from the problem:

Equation:

\text{Given: } V = ${v} \text{ V}, R = ${r} \text{ }\Omega

Calculation:

V=12 VR=100 ΩV = 12 \text{ V} \\ R = 100 \text{ }\Omega

Explanation:

We start by identifying what values we know and what we need to find.

2

Step 2: Apply Ohm's Law

Use Ohm's Law to find the current:

Equation:

I=VRI = \frac{V}{R}

Calculation:

I=12100=0.1200 AI = \frac{12}{100} = 0.1200 \text{ A}

Explanation:

Ohm's Law relates voltage, current, and resistance. To find current, we divide voltage by resistance.

3

Step 3: Calculate Power

Use the power formula to find power dissipation:

Equation:

P=V×IP = V \times I

Calculation:

P=12×0.1200=1.4400 WP = 12 \times 0.1200 = 1.4400 \text{ W}

Explanation:

Power is the rate at which electrical energy is converted to other forms of energy, calculated as voltage times current.

Frequently Asked Questions (FAQ)

What is Ohm's Law?

Ohm's Law states that the current through a conductor is directly proportional to the voltage across it and inversely proportional to its resistance: V = I × R.

When does Ohm's Law apply?

Ohm's Law applies to linear resistive elements where resistance remains constant regardless of voltage or current. It works well for most metallic conductors at constant temperature.

How do I calculate power in a circuit?

Power can be calculated using P = V × I, P = I²R, or P = V²/R. All three formulas give the same result when Ohm's Law applies.

What happens if I increase the voltage?

If resistance remains constant, increasing voltage will proportionally increase current according to Ohm's Law. Power will increase as the square of the voltage.

Why is resistance important?

Resistance limits current flow and determines how much voltage is needed to drive a given current. It also affects power dissipation and heat generation in circuits.

What happens when resistance is zero?

When resistance is zero (short circuit), current becomes infinite according to Ohm's Law. In practice, real circuits have some resistance, and very low resistance can cause high current and potential damage.

How do I use this calculator?

Enter any two values (voltage, current, or resistance) and the calculator will automatically calculate the third value. You can also enter all three values to verify they satisfy Ohm's Law.

Practice MCQs

  1. If voltage is 12V and resistance is 6Ω, what is the current?
  2. What is the power dissipated in a 10Ω resistor with 5A current?
  3. If current is 2A and resistance is 8Ω, what is the voltage?
  4. What happens to current if voltage doubles and resistance stays the same?
  5. Which formula is NOT a valid power equation?