Correct Option
The correct option is (a).
Explanation
The phenomenon where heat is produced due to the flow of electric current through a conductor is known as the heating effect of electric current. This is quantitatively governed by Joule’s Law of Heating, which states that the heat ($H$) produced in a resistor is directly proportional to the square of the current ($I$), the resistance ($R$), and the time ($t$) for which the current flows ($H = I^2Rt$).
Statement-wise Analysis
- Statement 1 is Correct: When an electric current passes through a wire, the electrons collide with the atoms of the conductor. These collisions transfer energy to the atoms, increasing their kinetic energy and resulting in the generation of heat. Thus, a wire gets hot when current passes through it.
- Statement 2 is Incorrect: The amount of heat produced does not depend solely on the magnitude of the current. According to the formula $H = I^2Rt$, the heat generated is also dependent on the resistance of the wire and the time duration for which the current flows.
- Statement 3 is Incorrect: The heat produced depends on the resistance ($R$) of the wire. Resistance is determined by the nature of the material (resistivity), the length, and the thickness (cross-sectional area) of the wire. Therefore, wires of different materials and thicknesses will produce different amounts of heat under the same current conditions.
Key Takeaway
Joule’s Law of Heating establishes that heat production in a conductor is dependent on three factors: the square of the current ($I^2$), the resistance ($R$) of the conductor (which varies with material and dimensions), and the time ($t$) of current flow.