Passage VII
When a temperature difference (△T) exists between the ends of an insulated metal rod (see Figure 1), heat flows from one end of the rod to the either. (△T = TH - TC, where TH and TC represent the temperature of the hotter end and the colder end, respectively.)
The rate at which heat flows is called the heat transfer rate, R.
The following data apply to insulated copper rods. Table 1 gives R versus △T for a 5 cm long rod with a cross-sectional area of 3 cm2. In Figure 2, R is plotted against length for rods having a △T of 30℃ and a cross-sectional area of 3 cm2. In Figure 3, R is plotted against cross-sectional area for 5 cm long rods with a △T of 30°C.
40. Based on the data in the passage, which of the following pairs of temperatures at the ends of identical insulated copper rods will result in the highest value of R?
TH TC
(°C) (°C)
Your Answer is
Correct Answer is F
Explanation
According to table 1, the bigger ΔT is, the bigger R will be. ΔT=TH-TC, option F has the largest ΔT, so R is also the largest