1. Fahrenheit and Celsius
Our Two Thermometers
Fahrenheit and Celsius

2. Vocabulary Boiling Point Freezing Point Degree Size Delta T
Calibration

3. Calibration
Calibrate means to determine or check the markings on a measuring instrument.

4. Calibration Celsius Fahrenheit 100 Boiling Point 212
0 Freezing Point

5. Calibration Celsius Fahrenheit 100 Boiling Point 212 100 C0 = 180 F0
0 Freezing Point

6. Size of Degrees So, 100 C0 = 180 F0 There are 100 C0 for every 180 F0.
and
1 C0 = 9/5 F0.

7. Size of Degrees If 1 C0 = 9/5 F0, then 1 F0 = 5/9 C0.
Which is the bigger degree?

8. Size of Degrees
A Celsius degree is larger. Notice that “one Celsius degree” (or “one Fahrenheit degree”) is written differently than “one degree Celsius” (or “one degree Fahrenheit”):
1C0 is a ∆T. 1 0C is a temperature. (You learned this on the second day of school.)

9. Conversions
First, let’s learn how to convert temperature differences (∆T’s). Then we’ll change one temperature to another.

10. Converting Temperature Differences (ΔTs)
The ending temperature is 25 0C. The beginning temperature was 5 0C. What is ∆T?
Convert this Celsius
∆T into a Fahrenheit ∆T.

11. Do It Like This. Step 1. ΔT = 25 0C - 5 0C ΔT = 20 C0
Step C0 x 9 F0/ 5 C0 = 36 F0

12. Converting Temperatures
F to C:
Use C= 5/9 (F - 32)
C to F:
Use F= 9/5 C + 32

13. Using C= 5/9 (F - 32) 1. Subtract 32 from the Fahrenheit temperature.
2. Multiply the difference by 5.
3. Divide the product by 9.
4. The quotient is the Celsius temperature.

14. Using F= 9/5 C + 32 1. Multiply the Celsius temperature by 9.
2. Divide the product by 5.
3. Add 32 to the quotient.
4. The sum is the Fahrenheit temperature.

15. Problems 1. Convert 100 0C to 0F. 2. Convert 0 0C to 0F.
4. Convert 180 0F to 0C.