1. What is Resistance?

Resistance is a measure of the opposition to current flow in an electrical circuit. It is measured in ohms (Ω). All materials resist current flow to some degree except superconductors which have zero resistance.

2. Understanding Ohm's Law

The fundamental relationship between voltage, current, and resistance is described by Ohm's Law:

Where:

• \( R \) — Resistance in ohms (Ω)
• \( V \) — Voltage in volts (V)
• \( I \) — Current in amperes (A)

Explanation: The resistance equals the voltage across a component divided by the current flowing through it.

3. How to Measure Resistance

Details: Resistance can be measured directly with an ohmmeter or calculated using Ohm's Law by measuring voltage and current. Always ensure power is off when measuring resistance directly.

4. Using the Calculator

Tips: Enter voltage in volts and current in amps. Both values must be positive numbers. The calculator will compute the resistance using Ohm's Law.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between resistance and impedance?
A: Resistance applies to DC circuits, while impedance (which includes resistance) applies to AC circuits and accounts for reactance.

Q2: Why does resistance increase with temperature?
A: In most conductors, increased temperature causes atoms to vibrate more, making it harder for electrons to flow (higher resistance).

Q3: What materials have very low resistance?
A: Good conductors like silver, copper, and gold have very low resistance. Superconductors have zero resistance at very low temperatures.

Q4: How does wire thickness affect resistance?
A: Thicker wires have lower resistance because there's more cross-sectional area for electrons to flow through.

Q5: What is the unit for resistance?
A: The SI unit for resistance is the ohm (Ω). 1 ohm = 1 volt per ampere.