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.
21. If Nin had been 300 turns in Trail 4, Uout would most likely have been:
Your Answer is
Correct Answer is A
Explanation
It can be seen from table 1 that Nin: Nout=Vin: Vout (the letter V is used here to replace the Greek letter representing voltage in the article), so when Nin in trail 4 becomes 300 turns, Vout=30 ×(50/300)=5 V, so choose A to meet