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Grade 7 Science

Grade 7 Science. Unit 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?. An Experiment.

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Grade 7 Science

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

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

  3. An Experiment... Place one hand in cold water, one hand in “hot” water for 1 minute. Then at the same time put both hands in the luke warm water. Describe what each hand feels.

  4. Temperature • How hot or cold something is

  5. Complete Activity 4-1 A“Boiling Hot, Freezing Cold”Page 111

  6. standard Temperatures • The human body

  7. Boiling point of water • Freezing Point of water

  8. Comfortable room temperature

  9. Measuring Temperatures Early Thermoscopes... 1. Galileo’s Air Thermoscope: As the air heats, the liquids drops and rises when air is cooled.

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

  11. A Demo... Activity 4-1A “Building a Thermoscope” Page 121

  12. Temperature Scales • Scales are necessary for temperatures to be accurate and comparable.

  13. 3 commonly used scales are: • Fahrenheit • Celsius • Kelvin

  14. Fahrenheit • Developed by Daniel Fahrenheit • The first to be widely used

  15. Celsius • Developed by Anders Celsius. • Based on the freezing and boiling points of water.

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

  17. Measuring Devices 1. The Liquid-in-glass Thermometer The lab thermometer contains colored alcohol rather than mercury for safety.

  18. 2. 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.

  19. Can measure higher temperatures than typical thermometers.

  20. 3. The Resistance Thermometer (digital thermometers)

  21. 4. 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.

  22. Thermostat

  23. A Demo... Heating and Cooling a Bimetallic Strip

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

  25. Can be used to measure heat loss in your home

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