Class 10 Physics - Electricity

Electricity is a controllable and convenient form of energy for a variety of uses.

1. Electric Current and Circuit

The rate of flow of electric charges. $I = \frac{Q}{t}$ (SI Unit: Ampere, A)

2. Electric Potential and Potential Difference

Work done to move a unit charge from one point to another. $V = \frac{W}{Q}$ (SI Unit: Volt, V)

3. Ohm's Law

The potential difference across the ends of a metallic wire is directly proportional to the current flowing through it, provided its temperature remains the same. $V = IR$ (SI Unit of Resistance: Ohm, $\Omega$)

4. Factors on which Resistance Depends

1. Length (L): $R \propto L$
2. Area of Cross-section (A): $R \propto \frac{1}{A}$
3. Nature of Material.

$R = \rho \frac{L}{A}$ ($\rho$ is electrical resistivity)

5. Resistance in Series and Parallel

• Series: $R_s = R_1 + R_2 + R_3$
• Parallel: $\frac{1}{R_p} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3}$

6. Heating Effect of Electric Current

$H = I^2Rt$ (Joule’s law of heating)

⚡ Important SI Units to Remember

• Charge: Coulomb (C)
• Current: Ampere (A)
• Potential Diff: Volt (V)
• Resistance: Ohm ($\Omega$)
• Power: Watt (W)

Practice drawing the Circuit Diagrams carefully! 💡🔌