Grade 7 Science Unit 2: Heat
description
Transcript of Grade 7 Science Unit 2: Heat
Grade 7 ScienceUnit 2: Heat Chapter 4: Temperature describes how hot or cold an object is.
Describing Temperature
How does temperature affect your daily life?
Why do you feel warm playing outside on a cold winter’s day?
TemperatureA description of how hot
or cold something is.
Activity
4-1A Boiling Hot, Freezing Cold p. 111
Standard Temperatures
Room Temperature – 22 oC
Body Temperature - 37 oCBoiling Point of Water - 100 oC
Freezing Point of Water - 0 oC
Air TemperatureRead p. 115 – 116
Reading Check p. 116 #1-3
Checkpoint
P. 119#6, 7, 8, 9
Measuring Temperature
Early Thermometers Galileo's Air
Thermometer▪ As the air heats, the liquids drops and rises when air is cooled.
Modern Day Galileo Thermometer
Early Thermometers
Early Liquid Thermometer: Liquid rising up the tube shows the temperature is rising.
Temperature ScalesScales are necessary for temperatures to be accurate and comparable.
3 commonly used scales are:1.Fahrenheit2.Celsius3.Kelvin
Fahrenheit Scale
Developed by Daniel Fahrenheit
The first to be widely usedFreezing of water occurs at 32 oF
Boiling of water occurs at 212 oF
Kelvin Scale
Developed by William Thomson (Lord Kelvin)
Scale states that the coldest temperature possible –absolute zero (-273 ˚C)
Celsius Scale
Developed by Anders Celsius Most commonly used temperature
scale Based on water freezing at 0 oC and
boiling at 100 oC .
Calibrating a Thermometer
To calibrate means to accurately assign a scale.
Steps to calibrating a Thermometer1.Place the bulb in a mixture of water
and ice.2.Mark the point at the top of the liquid
as 0 oC .3.Remove the bulb from the ice water
and place in boiling water. 4.Mark the point at the top of the liquid
as 100 oC 5.Divide the space between 0 and 100
into 100 even spaces. Each space will represent 1 oC .
Measuring Temperature Liquid in Glass Thermometer
The lab thermometer contains colored alcohol rather than mercury for safety.
Thermocouple
The Thermocouple Made of two wires of different metals. A temperature difference causes a
current to flow through the wires. This current is measured by a meter.
Can measure higher temperatures than typical thermometers.
The Resistance Thermometer (digital thermometers)
Bimetallic Strip (thermostat)
Made of two different metals fused together.
These metals expand and contract at different rates causing the strip to bend when heated.
Bimetallic Strip
Infrared Thermometer (thermogram)
Converts infrared radiation into colors that can interpret a temperature difference.
Checkpoint
P. 131#2, 3, 5, 6, 8, 12
P. 132 - 133#2, 10, 11, 15, 16, 18, 19