Unit 3 Heat & Temperature

Un i t 3H e a t &

Te m p e r a t u r e

Un i t 3To p i c 1 -

U s i n g H e a t

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?

Using Heat 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

Un i t 3Topic 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!

The Original Duckface!

I wonder if this will

catch on?!

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

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…

Oh my God where are your feet?!

What? Ahhh!!Who cares … what

we need to talk about it is

temperature!

I agree, my feet are now in the past and

this is present!We need a new

temperature scale!

That’s right, as scientists we need

to know the absolute coldest

temperature!

What do you think that would be Lord

Kelvin?

Ah you know I have been dubbed Lord Kelvin even though my name is William

Thomson!

Everyone knows, you don’t shut up

about it!

Well I am proud of it. Alright back to

work here…

…Carry the 1, factor in the sea level …

atmospheric pressure … aha!

12 … 23/2.34 + 9*Insert complexMath equations* …. = -273.15oC!

Has anyone ever froze something to

that recorded temperature?

No, but the math works out!

As my great math teacher Mr. Cox said

“You can’t argue math!”

So if we put this into a new temperature

scale…

…we call it the Kelvin scale!

Shotgun!

Shoot … wasn’t fast enough!

Also, we are calling the unit of measure

Kelvins! Boom!Ahh man!

Also the scale looks like this! Also,

because Lord Kelvin says so!

That’s a good looking scale right

there!Ahh! Who said

that?

Seriously Kelvin, for a smart man you need to get it together! I bet they teach this stuff in schools

later!

My legacy will live on forever!

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?