Victory for the ACT Student Text 15e

S CIENCE Q UIZZES • 335

EXPLANATIONS

12. After studying the measurement made in the previous question, as well as those made earlier in Experiments 1, 2, and 3, the experimenter could reasonably hypothesize that: F. voltage measured across a resistor is inversely proportional to the value of that resistor. G. voltage measured across a resistor is directly proportional to the value of that resistor. H. voltage measured across a resistor is not related to the value of that resistor. J. voltage measured across a resistor equals the battery voltage. When the experimenter recorded the current in the circuit of Experiment 1, it measured 0.003 amperes. In Experiment 3, however, the current measured 0.002 amperes. These results show that current and total resistances are: A. directly proportional. B. inversely proportional. C. equal. D. unrelated. 14. Which of the following expressions for the current in the circuit best summarizes the results of all three experiments? (The battery voltage is given by V b and the total resistance is given by R .) F. V b R G. V R b H. R V b J. V R b 13.

12. (G) Science/Evaluation of Models/Analysis A directly proportional relation- ship between voltage and resistance is shown in all three experiments: & ,1 000 3 R R 1, 000 ohms ohms V V 3 volts volts 2 1 2 1 , & ,1 000 R R 1, 000 ohms ohms V V 2 1 2 1 6 6 volts volts , and & ,2 000 4 R R 1, 000 ohms ohms V V 2 volts volts 2 1 2 1 .

13. (B) Science/Interpretation of Data/Analy- sis Experiments 1 and 3 demonstrate that if the resistance is increased, the current decreases (2,000 ohms/0.003 amperes; 3,000 ohms/0.002 amperes).

14. (H) Science/Interpretation of Data/ Analy- sis Based on the experimental results, current and resistance are inversely proportional , current resistance 1 ? c m and current and voltage are directly proportional current voltage ? ^ h . Thus, the formula relating the three variables is: current ? ? R V resista ce voltage b .