Define resistance and mention its unit.

Simple Answer:

Resistance is the property of a material that opposes the flow of electric current in a circuit. It controls how much current can pass through a conductor. Materials like metals have low resistance, while materials like rubber have high resistance.

The unit of resistance is ohm (Ω), named after Georg Simon Ohm, a scientist who discovered Ohm’s Law. One ohm is defined as the resistance when one volt of voltage causes one ampere of current to flow through a material.

Detailed Explanation:

Resistance is an important concept in electricity that affects how electrical devices work. It determines how easily or difficultly current can flow through a circuit.

What is Resistance?

  • Resistance is the opposition to the flow of electric current in a conductor.
  • It is measured in ohms (Ω) and represented by the symbol R.
  • It depends on the material, length, thickness, and temperature of the conductor.
  • A high resistance means less current flows, while a low resistance allows more current to pass.

Factors Affecting Resistance:

  1. Material: Conductors (like copper and aluminum) have low resistance, while insulators (like rubber and glass) have high resistance.
  2. Length of the Conductor: Longer wires have higher resistance because electrons have to travel a longer distance.
  3. Cross-Sectional Area: Thicker wires have lower resistance because they allow more space for electrons to flow.
  4. Temperature: Resistance increases with temperature in most materials.

Unit of Resistance – Ohm (Ω):

  • The unit of resistance is ohm (Ω).
  • One ohm is defined as the resistance when a voltage of 1 volt produces a current of 1 ampere.
  • The formula for resistance using Ohm’s Law is:

R=VIR = \frac{V}{I}R=IV​

Where R is resistance, V is voltage, and Iis current.

Examples of Resistance in Daily Life:

  1. Light Bulbs: The filament inside a bulb has high resistance, which produces light and heat when current flows through it.
  2. Electric Heaters: These work by converting electrical energy into heat using high-resistance coils.
  3. Wires in Circuits: Low-resistance wires like copper are used in electrical wiring to reduce energy loss.
Conclusion:

Resistance is the opposition to the flow of current in a circuit. It is measured in ohms (Ω) and plays a crucial role in controlling electrical circuits. Understanding resistance helps in designing efficient electrical systems and choosing the right materials for safe electricity usage.