试题与答案

长为L的导线ab斜放(夹角为θ)在水平轨道上,轨道平行间距为d,通过ab的电流强

题型:选择题

题目:

长为L的导线ab斜放(夹角为θ)在水平轨道上,轨道平行间距为d,通过ab的电流强度为I,匀强磁场的磁感应强度为B,如图所示,则导线ab所受安培力的大小为    

A.IdB/cosθ

B.IdB/sinθ

C.ILBsinθ

D.ILB

答案:

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题型:阅读理解

阅读理解

     George Stephenson's father was a stoker(司炉)of a coal engine near Newcastle upon Tyne in English.When George was fourteen he became his father's assistant at a shilling a day.He loved engines and spent all his spare time studying them.That was in 1795, and in those days all steam engines were stationary

(固定的). They were used to pull trucks along rails with a chain or rope.

     In 1804, Richard Trevithick built an engine on wheels, and several other engineers built locomotives

(火车头), as they were called, each one trying to make a better machine than the others.George

Stephenson himself tried to build a locomotive.

     Stephenson built his first locomotive in 1814, and he kept on trying to improve it.When the first public

railway was opened between Stochton and Darlington in 1825, it was his engine, called Locomotion, that pulled the first goods train in the world, with a few passengers on board.

     Stephenson's most famous engine was The Rocket, which his son Robert helped to design.In 1829, a

prize of 500 pounds was offered to the designer of the best locomotive.Five engines took part in the tests

and The Rocket proved to be the best in every way.It astonished everyone by pulling a train at the

wonderful speed of 30 miles an hour.With Robert, George Stephenson became the leading railway

engineer in the world, both for building engines and making railways.English had interesting names in those days, and the very famous one was called Puffing Billy.

1. George Stephenson's interest in engines started from________.

A. his love of engines at his time

B. his study of engines at spare time

C. his oneshilling income from his father

D. his experience of working with his father

2. Stephenson began to work on locomotives at the time when________.

A. some kinds of locomotives had already been built

B. no one could build a better one than his

C. only Trevithick made an engine on wheels

D. engines on wheels were not known as locomotives

3. Engines could be used to carry passengers________after the building of engines on wheels.

A. ten years  

B. twentyfive years

C. twentyone years  

D. thirty years

4. The Rocket aroused people's interest because it________.

A. won the prize

B. could run much faster

C. was the best of the five locomotives

D. was designed by Stephenson

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