Passage V

A material is a superconductor (its electrical resistance, R, is zero) if its temperature, T, is lower than its critical temperature, Tc.

Students measured R and T for both a sample of Material X and a sample of Material Y while each sample was cooled. They used an ohmmeter to measure R (in ohms) and a thermocouple to measure T. The thermocouple displayed the result of each measurement of T as a voltage (in millivolts, mV). Accordingly, the students plotted R versus voltage (see Figure 1). To convert voltage in mV to T in kelvins (K), they used Table 1.

Figure and table adapted from "instruction Manual for Superconductor Demonstrations." @1992 by Colorado Superconductor, Inc.

23. Based on Table 1, if the thermocouple were used to measure the temperature of a sample at 112 K, the voltage displayed would most likely be closest to which of the following ?

Answer and Explanation

Your Answer is

Correct Answer is B

Explanation

First of all, table 1 is a magical chart, which is relatively rare in the ACT science test. Please pay attention to the instructions marked with asterisks in the bottom two lines of the table. Take this question as an example, 112 K corresponds to the row 110, and the value in the column 2 is 5.09 mV