Question

What is Ohm's law? Explain by drawing the associated circuit diagram. Also discuss the terms on which the resistance of an electrical conductor depends.

Hint:

Ohm’s law is a fundamental relationship in electrical circuits and is useful for calculating voltage, current, or resistance when two of the three variables are known.

Answer 1

Ohm's Law:
Ohm's law states that the current \( I \) flowing through a conductor is directly proportional to the voltage \( V \) across it and inversely proportional to the resistance \( R \) of the conductor. Mathematically, it is expressed as: \[ V = I R \]
where:

- \( V \) is the potential difference (voltage) across the conductor (in volts),
- \( I \) is the current flowing through the conductor (in amperes),
- \( R \) is the resistance of the conductor (in ohms).

Terms on which the resistance of an electrical conductor depends:
The resistance \( R \) of a conductor depends on the following factors:
1. Material of the conductor:
Different materials have different resistances. For example, copper and aluminum have low resistance, while rubber and glass have high resistance.
2. Length of the conductor:
The resistance of a conductor is directly proportional to its length. The longer the conductor, the higher the resistance. \[ R \propto l \] Where \( l \) is the length of the conductor.
3.Cross-sectional area of the conductor:
The resistance of a conductor is inversely proportional to its cross-sectional area. A larger cross-sectional area leads to lower resistance. \[ R \propto \frac{1}{A} \] Where \( A \) is the cross-sectional area of the conductor. 4.
Temperature:
The resistance of most conductors increases with temperature. As the temperature rises, the atoms in the conductor vibrate more, causing more collisions with electrons, thus increasing the resistance.
Conclusion:
Ohm's law relates voltage, current, and resistance in a conductor. The resistance of a conductor depends on its material, length, cross-sectional area, and temperature.