A copper rod and a wooden rod each have a small blob of wax stuck near one end. The far ends are heated equally. On which rod does the wax melt, showing it ...
Question 1 Report
A copper rod and a wooden rod each have a small blob of wax stuck near one end. The far ends are heated equally. On which rod does the wax melt, showing it conducts heat well?
Answer Details
The wax melts on the copper rod, because copper is a metal and metals are good conductors of heat. The delocalised electrons in a metal are free to move, so they gain kinetic energy at the hot end and carry it rapidly along the rod, and the vibrating lattice of ions passes energy on as well. Energy therefore reaches the wax blob quickly and melts it.
Wood has no free electrons. Its energy can only be passed slowly from one vibrating molecule to the next, so it is an insulator and its wax stays solid. That is exactly why saucepans have metal bases and wooden or plastic handles.
Saying both rods behave the same ignores the whole point of the fair test set up here.
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