Which of the following is an example of heat transfer by conduction?

The example of heat transfer by conduction is represented by a rod that is heated on one end and becomes warm at the other end. This process occurs because conduction is the transfer of heat through a solid material without the movement of the material itself. When one end of the rod is heated, the heat energy is transferred through the material of the rod from the hot end to the cooler end where molecules vibrate and collide with adjacent molecules, effectively transferring energy along the length of the rod.

Other options illustrate different mechanisms of heat transfer. For instance, the cooling of warm air near a window involves convection, which is the transfer of heat through the movement of fluids (in this case, air). Steam heating a soup pot represents heat transfer by convection as well, where steam, a gas, transfers heat to the liquid in the pot. Heat rising from a flame is an example of convective heat transfer as well because it involves the movement of hot air rising upward due to its lower density compared to cooler air. Thus, the correct choice distinctly represents conduction, while the others illustrate convection or related processes.