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Unit 3 Heat & Temperature
Unit 3 Topic 1-Using Heat
Using Heat For Energy • Since the beginning of time we have used for fire for a variety of things… • Cooking • Protection • Construction • Heating • The list goes on …
Using Heat For Energy • How do you think our school is heated? • How is your home heated? • How do you cook your foods at home?
UsingHeat For Energy • The beautiful part about our world is that it is constantly changing and technologies are improving • Everything is being upgraded and improved for better efficiency and smaller ecological footprints
Unit 3 Topic 2-Measuring Temperature
Measuring Temperature • What is temperature? • A number that tells you how hot or cold something is • While this is the practical everyday definition science looks at temperature differently • What about estimating temperature? • What do we do, often without thinking to estimate the temperature of something?
Thermometers • What is thermometer? • Mechanical or electrical devices used to measure temperature accurately • The first thermometer was invented around 1600 by Galileo who was an Italian scientist • The design was then improved about 100 years later by making it more portable and using different liquids • What are these thermometers missing?
Measuring Temperature • If you said “scales” you are a genius! • The other thermometers gave general ideas but as we grew as a population and society and technologies improved we needed more accuracy! • We needed a standard unit of measure • Enter Anders Celsius! I wonder if this will catch on?! The Original Duckface!
Measuring Temperature • The Celsius Scale is almost universal … *Cough* America *Cough* • So how did he come up with this scale? • He used what was around him and made some observations about it • What was that? • Water! • So what do you think he did?
Measuring Temperature • As smart as that was we need to remember one important thing about water … • It is picky! • Changes in pressure and purity will effect water’s boiling and freezing point • In Alberta are we above or below sea level? • Right, above sea level • How does this affect how we boil water? • Water in Alberta actually boils several degrees less than 100oC!
Measuring Temperature • So what this caused scientists to do was go… Has anyone ever froze something to that recorded temperature? Well I am proud of it. Alright back to work here… I agree, my feet are now in the past and this is present! Ah you know I have been dubbed Lord Kelvin even though my name is William Thomson! What? Ahhh!! Also, we are calling the unit of measure Kelvins! Boom! As my great math teacher Mr. Cox said “You can’t argue math!” Also the scale looks like this! Also, because Lord Kelvin says so! …we call it the Kelvin scale! Shotgun! That’s right, as scientists we need to know the absolute coldest temperature! Ahh man! So if we put this into a new temperature scale… Who cares … what we need to talk about it is temperature! Oh my God where are your feet?! No, but the math works out! We need a new temperature scale! What do you think that would be Lord Kelvin? …Carry the 1, factor in the sea level … atmospheric pressure … aha! Shoot … wasn’t fast enough! Everyone knows, you don’t shut up about it! Seriously Kelvin, for a smart man you need to get it together! I bet they teach this stuff in schools later! That’s a good looking scale right there! My legacy will live on forever! Ahh! Who said that? 12 … 23/2.34 + 9 *Insert complex Math equations* …. = -273.15oC!
Measuring Temperature • So we now know a lot about thermometers • Can you use the same type of thermometer in any environment? • Actually you cannot … accurately that is! • You need your thermometer to have special components for it’s specific use and these components are … • Sensor • Material affected by the change in some feature of the environment
Measuring Temperature • Signal • Information signal about temperature that is generated and transmitted • Responder • Device (light, pointer, liquid) that receives the signal and uses/responds in some way to it • So what are some examples of different and unique thermometers?
Measuring Temperature • Thermocouple • Two different metal wires twisted together • When wire tips are heated they produce an electrical signal that travels throughout the wires • *The amount of current depends on the temperature* • This current is connected to a probe or a computer • The current gets too high it can trigger valves, switches • Unique for how high of a temperature it can record, normal thermometers would boil and break
Measuring Temperature • Bimetallic Strip • Two different metals joined firmly together • As it is heated one metal expands more than the other and it coils more tightly • When it is cooled the process is reversed • The movement of the strip can operate electrical switches • Used for example in air conditioners, furnacesand fridges
Measuring Temperature • Bimetallic Strip
Measuring Temperature • Recording Thermometer • Uses a bimetallic coil attached to a long metal lever that holds a special pen • The tiny movements of the coil translate to larger movements on the pen • The pen traces a line up and down along the spinning drum • The drum does 1 full turn every 7 days so it can track weekly temperature changes
Measuring Temperature • Recording Thermometer
Measuring Temperature • Infrared Thermogram • Anything warmed than absolute zero gives off infrared radiation (IR) • IR is similar to light but cannot be seen with the naked eye • You skin can detect it though through touch (warm) • You can capture it on video using special cameras and sensors • The colour and brightness of the image tells you about the temperature
Measuring Temperature • Infrared Thermogram
Measuring Temperature • Knowledge Test Is this video real or fake?