PACE WORK 07/10/20

 

Тема:Види струму

 LanguagePractice.

Teacher: Many devices could not have been invented without the discovery of electromagnetism. Many appliances use electromagnets. An electromagnet is a magnet which gets its  magnetism from induction.

 

Teacher: guess the answer when you listen to the description of the device:

(Telegraph, telephone, the electric motor, generator, doorbell, hearing aid)

1)      a telecommunications device that permits two or more users to conduct a conversation when they are not in the same vicinity of each other to be heard directly

2)       the long distance transmission of textual/symbolic (as opposed to verbal or audio) messages without the physical exchange of an object bearing the message

3)      an electrical machine that converts electrical energy into mechanical energy

4)       a device that converts mechanical energy to electrical energy for use in an external circuit

5)      a signaling device typically placed near an entry door to a building

6)      an electroacoustic device which is designed to amplify sound for the wearer, usually with the aim of making speech more intelligible

Students answer

4.2. Reading

Pre-reading:

Teacher: How do you understand the term electricity?

While-reading:

Teacher:Read the text on the topic and make up questions concerning the material.

Electriccurrentistheflowofelectrons, butelectronsdonotjumpdirectlyfromtheoriginpointofthecurrenttothedestination. Instead, eachelectronmoves a shortdistancetothenextatom, transferringitsenergytoanelectroninthatnewatom, whichjumpstoanotheratom, andsoon.Theindividualelectronsdonotmovequickly, butthecurrentitselfmovesatthespeedoflight. Currentflowheatsuptheconductor. Thismechanicproduceslightinlightbulbsandheatinelectricstovetops.

DirectCurrent

Directcurrentiselectriccurrentthatonlyflowsinonedirection. A commonplacetofinddirectcurrentisinbatteries. A batteryisfirstchargedusingdirectcurrentthatisthentransformedintochemicalenergy. Whenthebatteryisinuse, itturnsthechemicalenergybackintoelectricityintheformofdirectcurrent. Batteriesneeddirectcurrenttochargeup, andwillonlyproducedirectcurrent.

AlternatingCurrent

Alternatingcurrent, asthenameimplies, alternatesindirection. Alternatingcurrentisusedfortheproductionandtransportationofelectricity. Thisisbecausewhenelectricityisproducedinlargescale, suchasin a powerplant, ithasdangerouslyhighvoltage. Itiseasierandcheapertodowngradethiscurrenttolowervoltageforhomeusewhenthecurrentis AC. However, therewasanotherfactorthathelpeddeterminethechoiceof AC asthecurrentofchoicefordomesticconsumption. Inthelate 19th century, anindustrialstrugglebetweentheWestinghouseCompany, whichused AC, andGeneralElectric, whichused DC, endedinAC'sfavorwhenWestinghousesuccessfullylitthe 1893 ChicagoWorld'sFairusing AC. Sincethen, alternatingcurrentpowershomesandanythingelsethatdrawsonthecurrentinpowerlines.

 

Post-reading:

After reading you will ask your questions and fill in the blanks with the correct answers:

1.      One important device using electricity is _____

2.      What is an electromagnet?______

3.      Who was the first to discover that an electric current could produce magnetism?____

4.      Every electromagnet has ____ poles.

 

You are to compose short dialogues “Electricity in our life” using the key terms of the lesson.

Work in pairs.