# Chapter 4: Temperature describes how hot or cold an object is.

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Chapter 4: Temperature describes how hot or cold an object is.

 How does temperature affect your daily life?  Why do you feel warm playing outside on a cold winter’s day?

 A description of how hot or cold something is.

 4-1A Boiling Hot, Freezing Cold p. 111

 Room Temperature – 22 o C  Body Temperature - 37 o C  Boiling Point of Water - 100 o C  Freezing Point of Water - 0 o C

 Read p. 115 – 116  Reading Check p. 116 #1-3

 P. 119  #6, 7, 8, 9

 Early Thermometers  Galileo's Air Thermometer ▪ As the air heats, the liquids drops and rises when air is cooled.

 Early Liquid Thermometer:  Liquid rising up the tube shows the temperature is rising.

 Scales are necessary for temperatures to be accurate and comparable.  3 commonly used scales are: 1.Fahrenheit 2.Celsius 3.Kelvin

 Developed by Daniel Fahrenheit  The first to be widely used  Freezing of water occurs at 32 o F  Boiling of water occurs at 212 o F

 Developed by William Thomson (Lord Kelvin)  Scale states that the coldest temperature possible –absolute zero (-273 ˚C)

 Developed by Anders Celsius  Most commonly used temperature scale  Based on water freezing at 0 o C and boiling at 100 o C.

 To calibrate means to accurately assign a scale. Steps to calibrating a Thermometer 1. Place the bulb in a mixture of water and ice. 2. Mark the point at the top of the liquid as 0 o C. 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 o C 5. Divide the space between 0 and 100 into 100 even spaces. Each space will represent 1 o C.

 Liquid in Glass Thermometer  The lab thermometer contains colored alcohol rather than mercury for safety.

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.

 Made of two different metals fused together.  These metals expand and contract at different rates causing the strip to bend when heated.

 Converts infrared radiation into colors that can interpret a temperature difference.

 P. 131  #2, 3, 5, 6, 8, 12  P. 132 - 133  #2, 10, 11, 15, 16, 18, 19

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