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Grade 7 Science Unit 2: Heat

Chapter 4: Temperature describes how hot or cold an object is. Grade 7 Science Unit 2: Heat . Describing Temperature. How does temperature affect your daily life? Why do you feel warm playing outside on a cold winter’s day?. Temperature. A description of how hot or cold something is.

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Grade 7 Science Unit 2: Heat

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  1. Chapter 4: Temperature describes how hot or cold an object is. Grade 7 ScienceUnit 2: Heat

  2. Describing Temperature • How does temperature affect your daily life? • Why do you feel warm playing outside on a cold winter’s day?

  3. Temperature • A description of how hot or cold something is.

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

  5. Standard Temperatures • Room Temperature – 22 oC • Body Temperature - 37oC • Boiling Point of Water - 100oC • Freezing Point of Water - 0oC

  6. Air Temperature • Read p. 115 – 116 • Reading Check p. 116 #1-3

  7. Checkpoint • P. 119 • #6, 7, 8, 9

  8. Measuring Temperature • Early Thermometers • Galileo's Air Thermometer • As the air heats, the liquids drops and rises when air is cooled.

  9. Modern Day Galileo Thermometer

  10. Early Thermometers • Early Liquid Thermometer: • Liquid rising up the tube shows the temperature is rising.

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

  12. Fahrenheit Scale • Developed by Daniel Fahrenheit • The first to be widely used • Freezing of water occurs at 32 oF • Boiling of water occurs at 212 oF

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

  14. Celsius Scale • Developed by Anders Celsius • Most commonly used temperature scale • Based on water freezing at 0 oC and boiling at 100 oC .

  15. Calibrating a Thermometer • To calibrate means to accurately assign a scale. Steps to calibrating a Thermometer • Place the bulb in a mixture of water and ice. • Mark the point at the top of the liquid as 0oC . • Remove the bulb from the ice water and place in boiling water. • Mark the point at the top of the liquid as 100 oC • Divide the space between 0 and 100 into 100 even spaces. Each space will represent 1 oC .

  16. Measuring Temperature • Liquid in Glass Thermometer • The lab thermometer contains colored alcohol rather than mercury for safety.

  17. 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.

  18. The Resistance Thermometer (digital thermometers)

  19. 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.

  20. Bimetallic Strip

  21. Infrared Thermometer (thermogram) • Converts infrared radiation into colors that can interpret a temperature difference.

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

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