学士学位英语阅读理解练习3

练习3

 

The electromagnet was invented in England by William Sturgeon, who took an iron rod and bent it into the shape of a horseshoe. This "horseshoe"was coated with varnish and a layer of copper wire was wrapped around it. An electric current was passed through the wire,thus making the rod magnetic. The rod was now, because of magnetic attraction, able to sup-port nine pounds of iron.

 

In the US, a scientist named Joseph Henry improved on Sturgeon's electromagnet by insulating the copper wire with silk. He was able to wrap many turns of wire around an iron core without danger of short circuits between the turns. His magnet could hold 2,300 pounds.

 

This experiment promoted Henry to try his hand at converting magnetism into electricity First he coiled some insulated wire around an iron bar, connecting both ends of the wire to a galvanometer. The iron bar was placed across the poles of the electromagnet. Then the coil of the electromagnet was connected to a battery. The galvanometer indicated a voltage, then dropped to zero. Henry signaled his assistant to disconnect the coil. The galvanometer showed that once again a voltage had been produced, although this time in the opposite direction. The principle of electromagnetic induction had thus been discovered. Unfortunately for Joseph Henry he did not publish his findings and someone else (Faraday) got the credit for this discovery.

 

1.Henry's electromagnet was     

[A] exactly like Sturgeon's

[B] an improvement over Sturgeon's

[C]more dangerous than Sturgeon's

[D] not as good as Sturgeon's

 

2.Henry was encouraged by his experiment     

[A]to insulate the copper wire

[B] to change magnetism into electricity

[C] to convert electricity into magnetism

[D] to avoid short circuits

 

3.He connected the wire to    

[A]a coil

[B] a galvanometer

[C] the poles of the electromagnet

D]an iron bar

 

4.The galvanometer indicated    

[A] that Henry's assistant had connected the wire

[B] that Henry had been able to produce a voltage

[C]zero,with no voltage ever produced

[D] the iron bar had been placed across the poles of the electromagnet

 

5.According to what appeared in print at that time    

[A] Joseph Henry discovered the principle of electromagnetic induction

[B] Joseph Henry falsely tried to claim credit for the discovery of the principle of electromagnetic induction

[C]Faraday discovered the principle of electromagnetic induction

[D] Henry's experiment with electromagnetic induction was a failure