Passage IV
A transformer is an electrical component used to increase or decrease voltage. In 3 experiments, a group of students studied transformers using the setup shown in Figure 1.
An input coil was wrapped Nin turns around one side of a core (a solid ring) and then connected to an ammeter (current-measuring device) and a power source. An output coil was wrapped Nout turns around the opposite side of the core and then connected to an ammeter and a voltmeter. Uin and Uout were the input and output voltages (in volts, V), respectively. Iin and Iout were the input and output currents (in milliamperes, mA), respectively.
Experiment 1
In Trials 1-12, the core was made of iron, and the power source was a generator of alternating current (AC; current that varies over time). The students measured Iin, Uout, and Iout for various combinations of Nin, Nout, and Uin (see Table 1).
Experiment 2
In Trials 13-17, the procedure followed in Trial 5 was repeated except that the core material was varied (see Table 2).
Experiment 3
The procedures followed in Trials 1-12 were repeated, except that the power source was a battery supplying direct current (DC; current that remains constant over time). The Iin results matched those of Experiment 1, but in every trial, Uout was 0 V and Iout was 0 mA.
20. One of the students concluded that as Uin increases, Iin also increases. The student most likely arrived at this conclusion based on the results of which of the following groups of trials?
Your Answer is
Correct Answer is H
Explanation
Looking at table 1, only the input voltage of trails 9-13 is increasing, and the input current is also increasing, so the students must draw conclusions based on these trails