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.

24. For a transformer like those tested in Experiments 1-3 to generate an output voltage, a phenomenon called induction must occur in the core. Based on the results of Experiments 1 and 3, induction occurred only in the trials with:

Answer and Explanation

Your Answer is

Correct Answer is F

Explanation

Look at the brackets in the third line of Experiment 3. The experiment uses DC direct current, and the last sentence of Experiment 3 mentions that the output voltage and output current are both 0, indicating that the transformer does not generate output. According to the title, if there is no output, there will be no induction;

The brackets in the second line of Experiment 1 indicate that the experiment uses AC alternating current. It can be seen from table 1 that the experiment has output voltage and Output current, indicating that there is induction