Question

On heating one end of a piece of a metal, the other end becomes hot because of

• A. energised electrons moving to the other end
• B. minor perturbation in the energy of atoms
• C. resistance of the metal
• D. mobility of atoms in the metal

Answer 1

The Correct Option is A

To understand why heating one end of a metal causes the other end to become hot, we must look at the process of heat conduction in metals. Metals are known for their excellent ability to conduct heat, and this property is primarily due to the behavior of electrons within the metal.

Here's a step-by-step breakdown of how heat conduction occurs in metals:

1. When one end of a metal piece is heated, the energy from this heat source is transferred to the electrons at that end.
2. As the electrons gain energy, they become "energised" and start moving more rapidly.
3. These energised electrons then collide with adjacent atoms and other electrons, effectively transferring their energy throughout the metal.
4. Since electrons in metals are free to move, this transfer continues from the hot end toward the cooler end, moving through the metal.
5. This movement of electrons and their energy transfer is what results in the entire piece of metal becoming warm, even at the end not directly exposed to the heat source.

As a result, the correct option that explains this phenomenon is: Energised electrons moving to the other end. This is because the free electrons play a crucial role in transferring thermal energy across the metal.

Let's briefly rule out the other options:

• Minor perturbation in the energy of atoms: While such perturbations may occur, they are not the primary reason for heat conduction in metals.
• Resistance of the metal: Resistance pertains to electrical conduction, not directly to how heat is conducted.
• Mobility of atoms in the metal: Atoms in a solid metal do not have significant mobility; it is the movement of electrons that facilitates heat transfer.

In conclusion, the phenomenon observed is due to the conduction of heat through the free electron movement in the metallic structure.