iGCSE Physics (0625) 2.3.1 Conduction-Exam Style Questions- New Syllabus
▶️ Answer/Explanation
Detailed solution:
Thermal conduction is the process where thermal energy is transferred through a medium via particle vibrations and electron movement.
A “good thermal conductor” has a high rate of thermal energy transfer, meaning heat travels through it much faster than through other materials.
Since all rods are the same size and submerged in the same hot water, the rod with the highest conductivity will reach the wax’s melting point temperature first.
The “bad thermal conductor” (insulator) resists heat flow, while the “moderate” conductor transfers it at a medium pace.
Therefore, the wax on the good thermal conductor will receive enough energy to melt before the others.
▶️ Answer/Explanation
Detailed solution:
When heater $X$ is on, the water above it is heated, becomes less dense, and rises, creating a convection current that efficiently transfers thermal energy upwards.
However, since hot water rises, convection cannot transfer heat downwards to the water below the heater.
Water is a poor thermal conductor, but conduction remains the only primary method for energy to move toward the bottom of the tank.
Because liquids are bad conductors, the water at the bottom stays cold for much longer than the water at the top.
Thus, the transfer is mainly via convection for the top half and conduction for the bottom half.
This corresponds to Row C.
▶️ Answer/Explanation
Detailed solution:
Thermal conduction is the process where heat is transferred through a solid material via atomic vibrations and electron movement. Metals are excellent conductors, while wood is a poor conductor (a thermal insulator). By using wood for the handle, the rate of thermal energy transfer from the hot pan to the user’s hand is significantly lowered. This prevents the handle from reaching high temperatures, ensuring safety during cooking. Since heat travels through the solid material of the handle, the primary mechanism being addressed is conduction rather than convection, which occurs in fluids. Therefore, wood is chosen specifically to reduce thermal energy transfer by conduction.