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.

23. Suppose that a trail were performed in which Nin = 50 turns, Nout = 300 turns, and Uin = 30 V AC. If the core were made of iron, which of the following combinations of Iin, Uout, and Iout would most likely result from this trail?

Answer and Explanation

Your Answer is

Correct Answer is B

Explanation

(The letter V is used here to replace the Greek letter representing voltage in the article) From table 1, we can see a rule that is Nin: Nout=Vin: Vout, so Vout=30×(300/50)=180 V;

You can also see another law Iin: I< sub>out=Nout: Nin, so Iin: Iout=300:50=6:1. Option B meets