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Science 9 > Unit 4 - Topic 4 > Flashcards

Unit 4 - Topic 4 Flashcards

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1
Q

Energy

A

Ability to do work

Appears in many forms

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2
Q

Kinetic energy

A

Heat, light, and energy of movement

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3
Q

Heating elements

A

Converts electrical energy into thermal energy

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4
Q

What produces thermal energy

A

Movement of molecules within a substance

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5
Q

Heat

A

Thermal energy that is transferred from a warmer substance to a cooler one

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6
Q

Eg of electrical energy —> heat

A

Hair drier
Oven
Light bulb

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7
Q

Electrical energy converted because

A

Moving charges meet resistance of metal conductor

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8
Q

Thermocouple

A

Loop of 2 wires made of dif types of metals that converts heat to energy

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9
Q

Junctions

A

Ends of wires used in thermocouple

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10
Q

How thermocouples work

A

Wires wrapped at junctions
When one junction heated, small electric current produced
Dif in temp causes current to flow one way

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11
Q

If temp dif between junction increases, current

A

Increases

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12
Q

If positions of hot and cold junctions reversed, current will move

A

In opposite direction

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13
Q

Basic principle of thermocouple + person + yr + name of principle

A

Thomas Johann Seebeck
1821
Seebeck Effect

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14
Q

What did Seebeck conclude + right/wrong

A

Any 2 metals could be used
Not correct
Only certain combinations work

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15
Q

Common combinations for thermocouples

A

Copper + constantan (copper nickel alloy)

Iron + constantan

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16
Q

Produce only small amount of current

A

Individual thermocouples

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17
Q

Individual thermocouple uses

A

Obtain accurate temp measurements where liquid thermometers cannot be used

18
Q

If u hook 2 wires leading from thermocouple to battery,

A

One will get hot and other will get cold

19
Q

Thermocouples uses

A

Sensors in safety and control devices for furnaces, hot water heaters, and electric ovens

20
Q

Thermo-electric generator

A

Plants that burn fossil fuels to produce electricity
Or
Device based on thermocouple that converts heat directly into electricity without moving parts

21
Q

Thermocouple-electric generator components

A

Thermopile
Gas burner/heat source
Aluminum cooling fins/heat pipe assemblies
Load

22
Q

Thermopile

A

Several thermocouples connected in series

23
Q

Thermopiles pros

A

Extremely reliable

Low-maintenance devices

24
Q

Why thermopiles used in remote locations

A

To generate limited quantities of electrical energy sufficient to power eg. Emergency communications equipment

25
Q

How thermocouple-electric generator works

A

Fuel injected and burned to produce heat on one side of thermopile
Other side kept cool w/ cooling fins
Potential dif created
Thermopile connected to load w/ 2 wires so produced electricity powers device
Burner has exhaust out terminal and cooling fins has rejected heat place too

26
Q

Temps in generator

A

Hot - 540 C

Cold - 140 C

27
Q

Output size of generators

A

Individual: 15 W - 550 W
Combination: up to 5000 W

28
Q

Global Thermoelectric

A

Industry-leading company based in Calgary

29
Q

Piezo (Greek)

A

Pressure or push

30
Q

Piezoelectric effect uses

A

Electric watches

Sound modules in “talking” greeting cards

31
Q

Piezoelectric crystal eg

A

Quartz

Rochelle salt

32
Q

Piezoelectric effect

A

Piezo crystal connected to potential dif
Crystal expands/contracts slightly
Any material touching crystal experiences pressure
Pressure creates solid waves or vibrations

33
Q

Link between electricity and pressure first investigated by who and when

A

Pierre (21) and Jacques Curie (24)

1880

34
Q

Modern researchers/piezoelectric crystal

A

Developed non-crystalline materials to move in response to electrical current
Have potential uses

35
Q

Joseph Bar-Cohen

A

American Physicist

Created robotic hand with four “fingers”

36
Q

Robotic hand + pros and cons

A

When voltage applied plastic fingers bend
Can only grip small objects under or equal to 10 g
Inexpensive
Durable light

37
Q

STM

A

Scanning tunnelling machine
One of few machines capable of producing images of individual atoms
Parts of STM must make movements of a few nanometers (10^-9m)
Use piezoelectric ceramic wafers
Move very slightly when low voltage applied

38
Q

Piezoelectric effect in reverse

A

Crystal compressed/pulled
Potential dif build up on opposite sides of crystal
Conductors attached to crystal connect it in circuit
Acts as source of electrical energy

39
Q

Reverse piezo effect uses

A

Barbecue lighter
Crystal microphones
Some types of pressure sensors use changing voltage from crystal to control much larger electric currents in amplifiers and recording equipment

40
Q

Barbecue lighter/piezo effect

A

Squeezing handle slams tiny hammer against crystal

Generates potential dif of thousands of volts and miniature lightning bolt across spark gap

41
Q

1927/Warren Morrison

A

Canadian engineer working for Bell Laboratories in US
Invented quartz clock
Quartz watch crystals act as miniature tuning forks
Vibrate 32 768 times per sec
Other cam vibrate more than 59 million times a sec

Science 9 (21 decks)

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