Temperature scales Class 11 Chapter-1
Temperature scales are a part of the chapter on Thermodynamics or Heat and Temperature in physics. These scales are used to measure temperature, and they have different reference points, which can lead to varying values of temperature for the same physical state.
The main temperature scales are :
1. Celsius Scale (°C):
The Celsius scale is widely used in daily life and in scientific contexts.
It is based on two reference points:
0°C: The freezing point of water.
100°C: The boiling point of water (at standard atmospheric pressure).
The unit of temperature is degree Celsius (°C).
2. Fahrenheit Scale (°F):
The Fahrenheit scale is commonly used in the United States and a few other countries.
The reference points are:
32°F: The freezing point of water.
212°F: The boiling point of water (at standard atmospheric pressure).
The unit of temperature is degree Fahrenheit (°F).
3. Kelvin Scale (K):
The Kelvin scale is the SI unit (International System of Units) for measuring temperature.
This scale is absolute, meaning it starts at 0 K, known as absolute zero, the theoretical lowest possible temperature where all molecular motion stops.
The reference points are:
0 K: Absolute zero (no motion of particles).
273.15 K: The freezing point of water.
373.15 K: The boiling point of water.
The Kelvin scale does not have negative values. Temperatures in Kelvin are written in K, with no degree symbol (°).
4. Rankine Scale (°R):
The Rankine scale is used mainly in engineering and thermodynamics in the United States.
It is similar to the Kelvin scale but uses the Fahrenheit degree size.
The reference points are:
0°R: Absolute zero.
The freezing point of water is 491.67°R.
The boiling point of water is 671.67°R.
The unit of temperature is Rankine (°R), similar to Fahrenheit but based on an absolute zero reference.
Conversion Between Scales:
Celsius to Kelvin: \( K = °C + 273.15 \)
Celsius to Fahrenheit: \( °F = \frac{9}{5} \times °C + 32 \)
Fahrenheit to Kelvin: \( K = \frac{5}{9} \times (°F - 32) + 273.15 \)
Why These Scales?
Celsius is useful for everyday life and in scientific experiments.
Fahrenheit is used mostly in the United States for weather, cooking, and household temperature measurements.
Kelvin is primarily used in scientific contexts, especially in thermodynamics, as it is based on absolute zero and is essential for calculations in physics.
Rankine is mostly used in engineering for thermodynamic systems.
These temperature scales are important in understanding the principles of heat and energy transfer, and they help in measurements related to the physical properties of substances in different states (solid, liquid, gas).
1. Which of the following is the SI unit for temperature?
a) Celsius
b) Kelvin
c) Fahrenheit
d) Rankine
Answer: b) Kelvin
2. What is the freezing point of water in the Celsius scale?
a) 0°F
b) 32°C
c) 32°F
d) 0°C
Answer: d) 0°C
3. Which scale uses absolute zero as its starting point?
a) Celsius
b) Fahrenheit
c) Kelvin
d) Rankine
Answer: c) Kelvin
4. What is the boiling point of water in the Fahrenheit scale?
a) 100°F
b) 212°F
c) 32°F
d) 0°F
Answer: b) 212°F
5. The Kelvin scale is also known as the __________ scale.
a) Centigrade
b) Absolute
c) Relative
d) Standard
Answer: b) Absolute
6. Which of the following temperature scales has no negative values?
a) Celsius
b) Fahrenheit
c) Kelvin
d) Rankine
Answer: c) Kelvin
7. The unit of temperature in the Rankine scale is __________.
a) °C
b) °F
c) K
d) °R
Answer: d) °R
8. What is the relationship between Celsius and Kelvin?
a) \( K = °C + 273.15 \)
b) \( K = °C - 273.15 \)
c) \( K = °C + 273 \)
d) \( K = °C - 273 \)
Answer: a) \( K = °C + 273.15 \)
9. The freezing point of water in the Fahrenheit scale is:
a) 0°F
b) 32°F
c) 100°F
d) -32°F
Answer: b) 32°F
10. What is the boiling point of water in the Celsius scale?
a) 0°C
b) 100°C
c) 32°C
d) 212°C
Answer: b) 100°C
11. Which scale is used for scientific calculations, especially in thermodynamics?
a) Celsius
b) Fahrenheit
c) Kelvin
d) Rankine
Answer: c) Kelvin
12. Which of the following statements about the Kelvin scale is true?
a) It is based on the freezing and boiling points of water.
b) It can have negative temperature values.
c) It starts at absolute zero.
d) It is commonly used in weather forecasting.
Answer: c) It starts at absolute zero.
13. In which scale is 0 K the lowest possible temperature?
a) Celsius
b) Fahrenheit
c) Kelvin
d) Rankine
Answer: c) Kelvin
14. Which of the following is true about the Rankine scale?
a) It starts at 0°C.
b) It uses the Fahrenheit degree for temperature measurement.
c) It is used in scientific experiments in physics.
d) It is based on the freezing and boiling points of water.
Answer: b) It uses the Fahrenheit degree for temperature measurement.
15. What is the freezing point of water in the Rankine scale?
a) 273.15°R
b) 491.67°R
c) 32°R
d) 0°R
Answer: b) 491.67°R
16. Which temperature scale is primarily used in the United States?
a) Celsius
b) Fahrenheit
c) Kelvin
d) Rankine
Answer: b) Fahrenheit
17. Absolute zero corresponds to ________ in the Kelvin scale.
a) -273.15°C
b) 0°C
c) -32°F
d) 0°F
Answer: a) -273.15°C
18. The Rankine scale is based on the Fahrenheit scale but starts at __________.
a) Absolute zero
b) Freezing point of water
c) Boiling point of water
d) Room temperature
Answer: a) Absolute zero
19. Which scale is commonly used in weather forecasting in countries that use the metric system?
a) Fahrenheit
b) Celsius
c) Kelvin
d) Rankine
Answer: b) Celsius
20. Which of the following is the correct formula to convert Celsius to Fahrenheit?
a) \( °F = \frac{9}{5} \times °C + 32 \)
b) \( °F = \frac{5}{9} \times °C + 32 \)
c) \( °F = \frac{9}{5} \times °C \)
d) \( °F = °C + 32 \)
Answer: a) \( °F = \frac{9}{5} \times °C + 32 \)
21. The difference in temperature between 0°C and 1°C is the same as the difference between which of the following on the Kelvin scale?
a) 0 K and 1 K
b) 273.15 K and 274.15 K
c) 0 K and 273.15 K
d) 1 K and 100 K
Answer: b) 273.15 K and 274.15 K
22. The conversion between Celsius and Kelvin is _________.
a) \( K = °C - 273.15 \)
b) \( K = °C + 273.15 \)
c) \( K = °C \)
d) \( K = 273.15 \times °C \)
Answer: b) \( K = °C + 273.15 \)
23. What is the boiling point of water on the Rankine scale?
a) 373.15°R
b) 100°R
c) 671.67°R
d) 212°R
Answer: c) 671.67°R
24. Which of the following is a characteristic of the Kelvin scale?
a) It is a relative scale, based on freezing and boiling points.
b) It does not allow negative temperature values.
c) It uses the Celsius degree for measurement.
d) It is most commonly used in everyday life.
Answer: b) It does not allow negative temperature values.
25. Which of the following temperature scales is most often used in scientific research?
a) Celsius
b) Kelvin
c) Fahrenheit
d) Rankine
Answer: b) Kelvin
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