Advanced Writing with English in Use

Processesandsystems • Module2C

2.1 Moreon cohesion

This textwaswritte n forschoo lsc ie nce students. The exercise focuses on

cohesion, including the features studied in2 .0.Completethe text by writing the

missingword in eachgap. Theexe rcise begins withan example(0 ).See page 9

for information andadviceaboutt his exercise type.

How a

metal

detector

works

Electronicmetaldetectorsusethe

principleofelectromagnetic

induction.(0) This

me an s tha t,ifano b jec tis placed in

a cha ng ing magn e ticfield, a n

electrical voltageiscreatedin

( 1) object.Ina

metaldetector,anelectrical curr e n t

is passedthrougha c o ilofwire,

c all e d the:search coil,

(2) c reatea

magn eti cfield.(3)'_~,To _

alte rn at ingcurrent(Ae)generator

convertsthedirectcurrent(DC)

fromth ebatteryintotheAC

neededtod rivethecoil.

(4 )-..,_, , ACregularly

re ve rsesd ire c tio n,itp roduce sth e

ne c e ssaryever-cha ng ingmagnetic

field.

Cu rrentsaregenerated,in a

metal object (5)__

comeswithintheruag ne ric fieldby

aprocess k nownasinduction.

When a curren t isinducedina

m etal ob jec t(fo r example , aburied

coin),( 6)-.., in turn

producesitsownmagneticfields.

(7), magn eti cfields

arecapableo f ind uci nga small

amou ntofelectricity in the

detector's search coilitself.

111esim p le stkindofmetal

detectoristhepulseinducti on

type. Apowerfu lc ur ren t ispassed

fromthebattery throug h the search

coil and( 8)

switchedoff. Thepulseof

magnetismcausescurrentsto flow

in anytarget ob jec tsbelowthe

ground. (9), , unlike

thecurrentin these arc hcoil, the

c ur rent inth eobjectc an no t be

sw itch edoff; it ( 10) _

to dieawaynaturally. Asit fades,

th e current intheobjectreacti vate s

th esearch coil. 111 is voltageis

( 11) amp li fied to

indicatewith a so u ndora flash ing

lighttha tan o b jecthasbeen found.

2.2 Writingpractice

The following advertisement appearedin the newsletterof The GreenCross,an

organization dedicated to promot ingmore efficient use ofthe world'snatural

resources andto reducingpolluti on.

A thousand and one ways to save the planet

Is everythinginyour town 100 %efficient?Thlnkof
rubbishcollection ,transport, of ficehours, recycling,
et c. Wbatever system you choose ,get t ogeth er wit h
some friends and findwaysinw hich it could be made
more efficient,eit he rsavi ngenergyo r reducin g
poll ut io n.Remember, "smallis beauti ful "- evenifyour

idea onlysaves a few calorie s, it's still part of a giant

step for mankind!Tbenw rite to us, describingtbe

presentsystem in detail ,andoutlin ingyour plansfo r

improvement. Thebest i deas we receive willbe

included in our newpubli cati on ,1,0 01 Ways To Save

The Planet ,andshould be about250 word s long.

Work in a groupto chooseanappropriatesystem and make it more efficient,

then writeyourideas so they can be included in the book.

Task bank;Tasks 8, 9, 35 and 40

Types of writing • 57