$[-/6$ Points$]$

POE$1$

$1998.$MC$.19.$

ASK YOUR TEACHER

One end of a metal rod of length $L$ and cross$-$sectional area $A$ is held at a constant temperature $T_1.$ The other end is held at a constant $T_2.$ Which of the statements about the amount of heat transferred through the rod per unit time are true?

I. The rate of heat transfer is proportional to $\frac{1}{T_1-T_2}.$

II$.$ The rate of heat transfer is proportional to $A.$

III. The rate of heat transfer is proportional to $L.$

II only

III only

I and II only

I and III only

II and III only