障碍跑雅思阅读

READING PASSAGE 1

You should spend about 20 minutes on Questions 1

–

13 which are based

on Reading Passage 1 below

.

William Gilbert and Magnetism

The

accredited

father

of

the

science

of

electricity

and

magnetism

was

the

English scientist, William Gilbert, who was a physician and man of

learning at the court of Elizabeth. Prior to him, all that was known of

electricity

and

magnetism

was

what

the

ancients

knew,

that

the

lodestone

possessed

magnetic

properties

and

that

amber

and

jet,

when

rubbed,

would

attract bits of paper or other substances of small specific gravity.

William

Gilbert's

great

treatise

De

magnete,

magneticisique

corporibus

or

, printed in Latin in 1600, containing the fruits of

his

researches

and

experiments

for

many

years,

indeed

provided

the

basis

for a new science.

William Gilbert was born in Colchester, Suffolk, on May 24, 1544. He

studied medicine at St. John's College, Cambridge, graduating in 1573.

He was prominent in the College of Physicians and became its president

in

1599.

The

following

year

he

was

appointed

physician

to

Queen

Elizabeth

I,

and

a

few

months

before

his

death

on

Dec.

10,

1603,

physician

to

James

I.

The

ancient

Greeks

knew

about

lodestones,

strange

minerals

with

the

power

to attract iron. Some were found near the city of Magnesia in Asia Minor

(now

Turkey),

and

that

city

lent

its

name

to

all

things

magnetic.

The

early

Chinese also knew about lodestones and about iron magnetized by them.

Around the year 1000 they discovered that when a lodestone or an iron

magnet

was

placed

on

a

float

in

a

bowl

of

water,

it

always

pointed

south.

From this developed the magnetic compass, which quickly spread to the

Arabs and from them to Europe.

Britain was a major

seafaring nation

in

1588 when the

Spanish Armada was

defeated,

opening

the

way

to

British

settlement

of

America.

British

ships

depended on the magnetic compass, yet no one understood why it worked.

Did the pole star attract it, as Columbus once speculated; or was there

a magnetic mountain at the pole, as described in

Odyssey

, which ships

should never approach, because the sailors thought its pull would yank

out all their iron

nails and

fittings?

Did the smell

of garlic interfere

with the action of the compass, which is why helmsmen were forbidden to

eat

it

near

a

ship's

compass?

For

nearly

20

years

William

Gilbert

conducted

ingenious experiments to understand magnetism.

NASA notes. Given two magnets, Gilbert knew that magnetic poles can

attract or repel, depending on polarity. In addition, however, ordinary

iron is always attracted to a magnet. Gilbert guessed, correctly, that

near a permanent magnet iron became a temporary magnet, of a polarity

suitable for attraction. That is, the end of an iron bar stuck to an S

pole of a magnet (south-seeking pole) temporarily becomes an N-pole.

Because

magnetic

poles

always

come

in

matched

pairs,

the

other

end

of

the

bar

temporarily

becomes

an

S-pole,

and

can

in

its

turn

attract

more

iron.

Gilbert confirmed his guess of temporary (

original

experiment.

Using

strings,

he

hung

two

parallel

iron

bars

above

the pole of a

terrella

, a model earth he designed for this experiment,

and noted that they repelled each other. Under the influence of the

terrella, each became a temporary magnet with the same polarities, and

the temporary poles of each bar repelled those of the other one.

In

1600

Gilbert

published

De

magnete

in

Latin.

Very

quickly

it

became

the

standard

work

throughout

Europe

on

electrical

and

magnetic

phenomena.

In

this work he describes many of his experiments with his model earth

terrella. From his experiments, he concluded that the Earth was itself

magnetic

and

that

this

was

the

reason

compasses

pointed

north.

In

his

book,

he also studied static electricity using amber. Gilbert strongly argued

that electricity and magnetism was not the same thing. For evidence, he

(incorrectly) pointed out that electrical attraction disappeared with

heat, magnetic attraction did not. By keeping clarity, Gilbert's strong

distinction advanced science for nearly 250 years. It took James Clerk

Maxwell

to

show

electromagnetism

is,

in

fact,

two

sides

of

the

same

coin.

De

Magnete

is

not

only

a

comprehensive

review

of

what

was

known

about

the

nature of magnetism, Gilbert added much knowledge through his own

experiments.

He

likened

the

polarity

of

the

magnet

to

the

polarity

of

the

Earth and built an entire magnetic philosophy on this analogy. In