Resistance is the opposition that a material offers to the flow of electric current. It slows down the movement of electrons in a circuit.

What Causes Resistance?

When electrons move through a wire, they collide with atoms inside the material. These collisions make it harder for the current to flow—this is what we call resistance.

Factors That Affect Resistance:

1. Material – Some materials, like copper, have low resistance and let electricity flow easily. Others, like rubber, have high resistance.

2. Length of the Wire – Longer wires have more resistance.

3. Thickness (Cross-sectional Area) – Thicker wires have less resistance.

4. Temperature – As temperature increases, resistance usually increases.

   
   

Formula:

Resistance (R) = Voltage (V) ÷ Current (I)Measured in ohms (Ω).

Example:

If a bulb has 6 volts across it and a current of 2 amps flows,Resistance = 6 ÷ 2 = 3 ohms

Resistance is not always a bad thing—in fact, it's very useful. Devices like heaters and toasters work by using high resistance wires that convert electrical energy into heat. . Resistors, which are small components in circuits, are used to control current flow, protect sensitive parts, and adjust signal levels. In some special materials called superconductors, resistance drops to zero at very low temperatures, allowing electricity to flow with no energy loss at all.