Page 43 - Ripples SCIENCE 7 - TEJPUR Edition 2024 Answer Key

7. What is the relation between °C, °F and kelvin?

Ans. Celsius (°C)
• It is a temperature scale commonly used in everyday life and scientific contexts.

• Water freezes at 0°C and boils at 100°C.
• The Celsius scale is based on dividing the temperature difference between the

freezing and boiling points of water into 100 equal parts.
Fahrenheit (° F)

• It is primarily used in the United States and a few other countries.
• Water freezes at 32°F and boils at 212°F. These are the lower & upper fixed

points of this scale.
• The interval between the two fixed points is divided into 180 equal parts and

each part is 1°F.
Kelvin (K)

• It is the SI unit of temperature.
• The lower and upper fixed points are 0 K and 273 K respectively.

• The scale is divided into 100 equal parts and each part is 1 K.
The Celsius scale is directly proportional to the Fahrenheit scale.

 100°C = 180°F
0°C = 32°F

° −
° −
( C 0) ( F 32)
∴ =
100 180
( °C× 180)
Or = F
° −332
100
9
−
Or ×° C = °F32
5
One unit increase in the Kelvin scale is the same as one-degree increase in the Celsius

scale.
The relationship between the two scales is as follows:

1°C = 273.15K

Water boils at 100°C, whereas on the Kelvin scale, it boils at 373.15 K.
K = °C + 273

8. Differentiate between clinical thermometer and laboratory thermometer.

Ans. Clinical thermometers are specifically designed for measuring body temperature.

These thermometers are typically small and portable, featuring a bulb containing
mercury or digital sensors. They are calibrated to measure a narrow temperature

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