1. What is a Resistor Calculator?

Definition: This calculator determines the appropriate resistor value needed based on voltage and current using Ohm's Law.

Purpose: It helps electronics hobbyists and engineers select the correct resistor for circuits and components.

2. How Does the Calculator Work?

The calculator uses Ohm's Law formula:

Where:

• \( R \) — Resistance (ohms)
• \( V \) — Voltage (volts)
• \( I \) — Current (amps)

Explanation: The voltage is divided by current to determine the required resistance value.

3. Importance of Proper Resistor Selection

Details: Correct resistor values prevent component damage, ensure proper circuit operation, and maintain desired current flow.

4. Using the Calculator

Tips: Enter the voltage across the resistor and the desired current through it. Both values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What if my calculated value isn't a standard resistor?
A: Use the next higher standard value or combine resistors in series/parallel to achieve the needed value.

Q2: How do I account for power dissipation?
A: Calculate power (P = V×I) and select a resistor with wattage rating at least 2× the calculated value.

Q3: What's the difference between AC and DC calculations?
A: For AC circuits with reactive components, impedance calculations are needed instead of simple resistance.

Q4: Can I use this for LED current limiting?
A: Yes, but subtract the LED's forward voltage from the supply voltage before calculating.

Q5: What tolerance should I choose?
A: For most applications, 5% tolerance is sufficient. Use 1% for precision circuits.