Q1.
In your Grade 6 Science textbook, Curiosity, you read about different types of thermometers used for measuring the temperature — the clinical thermometer and the laboratory thermometer. You also learnt about temperature scales. One of them is the Celsius scale; another is the Fahrenheit scale. If, for instance, we have a cool temperature of 15 degrees Celsius (noted as 15°C), it is the same as 59 degrees Fahrenheit (noted as 59°F).
Answer
Here is the Grade 6 idea in one place, ready to use in this chapter.
| Thermometer | What it measures | Usual range |
|---|---|---|
| Clinical thermometer | Body temperature of a person | about 35°C to 42°C |
| Laboratory thermometer | Temperature of things in an experiment | about −10°C to 110°C |
| Maximum–minimum thermometer | Highest and lowest air temperature of a day | used at weather stations |
The two scales are two different rulers for the same thing:
0°C = 32°F (ice melts)
15°C = 59°F (a cool day — the book's example)
100°C = 212°F (water boils)
°F = (°C × 9 ÷ 5) + 32
15°C = 59°F (a cool day — the book's example)
100°C = 212°F (water boils)
°F = (°C × 9 ÷ 5) + 32
Check the book's example: 15 × 9 ÷ 5 = 27, and 27 + 32 = 59. ✓
Why two scales exist: The Celsius scale fixes 0 at the melting point of ice and 100 at the boiling point of water, so it divides that gap into a neat 100 steps. The Fahrenheit scale was made earlier with different fixed points and divides the same gap into 180 steps. India, and almost every weather service in the world, reports in °C.
Tip: A weather thermometer must never be kept in direct sunlight. It would then record how hot the sunlit glass is, not how hot the air is.