Unit 4 - Topic 4

Question 1

Energy

Answer 1

Ability to do work

Appears in many forms

Question 2

Kinetic energy

Answer 2

Heat, light, and energy of movement

Question 3

Heating elements

Answer 3

Converts electrical energy into thermal energy

Question 4

What produces thermal energy

Answer 4

Movement of molecules within a substance

Question 5

Heat

Answer 5

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

Question 6

Eg of electrical energy —> heat

Answer 6

Hair drier
Oven
Light bulb

Question 7

Electrical energy converted because

Answer 7

Moving charges meet resistance of metal conductor

Question 8

Thermocouple

Answer 8

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

Question 9

Junctions

Answer 9

Ends of wires used in thermocouple

Question 10

How thermocouples work

Answer 10

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

Question 11

If temp dif between junction increases, current

Answer 11

Increases

Question 12

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

Answer 12

In opposite direction

Question 13

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

Answer 13

Thomas Johann Seebeck
1821
Seebeck Effect

Question 14

What did Seebeck conclude + right/wrong

Answer 14

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

Question 15

Common combinations for thermocouples

Answer 15

Copper + constantan (copper nickel alloy)

Iron + constantan

Question 16

Produce only small amount of current

Answer 16

Individual thermocouples

Question 17

Individual thermocouple uses

Answer 17

Obtain accurate temp measurements where liquid thermometers cannot be used

Question 18

If u hook 2 wires leading from thermocouple to battery,

Answer 18

One will get hot and other will get cold

Question 19

Thermocouples uses

Answer 19

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

Question 20

Thermo-electric generator

Answer 20

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

Question 21

Thermocouple-electric generator components

Answer 21

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

Question 22

Thermopile

Answer 22

Several thermocouples connected in series

Question 23

Thermopiles pros

Answer 23

Extremely reliable

Low-maintenance devices

Question 24

Why thermopiles used in remote locations

Answer 24

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

Question 25

How thermocouple-electric generator works

Answer 25

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

Question 26

Temps in generator

Answer 26

Hot - 540 C | Cold - 140 C

Question 27

Output size of generators

Answer 27

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

Question 28

Global Thermoelectric

Answer 28

Industry-leading company based in Calgary

Question 29

Piezo (Greek)

Answer 29

Pressure or push

Question 30

Piezoelectric effect uses

Answer 30

Electric watches | Sound modules in “talking” greeting cards

Question 31

Piezoelectric crystal eg

Answer 31

Quartz | Rochelle salt

Question 32

Piezoelectric effect

Answer 32

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

Question 33

Link between electricity and pressure first investigated by who and when

Answer 33

Pierre (21) and Jacques Curie (24) | 1880

Question 34

Modern researchers/piezoelectric crystal

Answer 34

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

Question 35

Joseph Bar-Cohen

Answer 35

American Physicist | Created robotic hand with four “fingers”

Question 36

Robotic hand + pros and cons

Answer 36

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

Question 37

STM

Answer 37

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

Question 38

Piezoelectric effect in reverse

Answer 38

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

Question 39

Reverse piezo effect uses

Answer 39

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

Question 40

Barbecue lighter/piezo effect

Answer 40

Squeezing handle slams tiny hammer against crystal | Generates potential dif of thousands of volts and miniature lightning bolt across spark gap

Question 41

1927/Warren Morrison

Answer 41

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