Temperature and its Measurement

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A–2, B–1, C–4, D–3, E–5

A–3, B–5, C–2, D–1, E–4

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Hint: A reliable measure of the hotness or coldness of a body; a hotter body has a higher temperature than a colder body.

Hint: The same water (container B) felt cool to one hand and warm to the other after dipping in warm and ice-cold water — the sense of touch can be misled.

Hint: Clinical thermometer — human body temperature; laboratory thermometer — many other purposes (measuring temperature of water, etc.).

Hint: To maintain hygiene and prevent the spread of germs between users.

Hint: Wash hands and tip with soap and water; keep the digital display out of water while washing; do not hold the thermometer by the tip; read the instruction manual first.

Hint: Normal temperature is an average of many healthy people; it varies with age, time of day and activity level.

Hint: 37.0 °C = 98.6 °F.

Hint: K = °C + 273.15; 25 °C = 298.15 K.

Hint: Celsius — degree Celsius (°C); Fahrenheit — degree Fahrenheit (°F); Kelvin — kelvin (K).

Hint: As per the convention in the chapter, the degree sign (°) is written with °C and °F but not with K.

Hint: Fever affects the pulse rate, which was known in olden India; but other situations also change pulse rate, so it is not a reliable indicator.

Hint: Alcohol coloured red (to be easily seen) or mercury.

Hint: –10 °C to 110 °C.

Hint: It is made of glass; if it hits a hard object it can break.

Hint: Handle with care (it can break); do not hold it by the bulb; keep it vertical; the bulb should not touch the bottom/sides of the beaker.

Hint: Once taken out, the liquid column begins to fall immediately, giving a wrong reading.

Hint: They give an approximate idea of the room temperature.

Hint: The maximum and minimum air temperature of the day.

Hint: An Indian scientist (1918–2001), known as the 'Weather Woman of India'; she invented and built many weather measurement instruments and explored wind and solar energy.

Hint: The lowest temperature that can be achieved, close to –273.15 °C (0 kelvin).

Introduction: An activity with three containers of water at different temperatures shows that our sense of touch is not always reliable.
Key Points:
1. Setup — Container A had warm water, B had tap water and C had ice-cold water.
2. Procedure — The right hand was dipped in A and the left in C for 1–2 minutes, then both hands were placed in B.
3. Inference — The right hand felt B cool and the left hand felt B warm, proving we cannot always rely on our sense of touch.
Conclusion: The same water giving different sensations shows that the sense of touch is not a reliable measure of temperature.

Introduction: Clinical and laboratory thermometers differ in their purpose, design and range of measurement.
Key Points:
1. Purpose — Clinical thermometers measure human body temperature, while laboratory thermometers measure temperatures of other substances.
2. Display and design — Clinical thermometers show digital displays and run on batteries; laboratory thermometers have a glass tube with a liquid column.
3. Range — Clinical thermometers have a range of about 35–42 °C, while laboratory thermometers typically range from –10 °C to 110 °C.
Conclusion: The two types of thermometers are designed differently to suit their specific measurement purposes.

Introduction: Measuring temperature with a laboratory thermometer requires following specific steps for accurate readings.
Key Points:
1. Bulb placement — The bulb should be immersed in the liquid without touching the bottom or sides of the beaker.
2. Vertical position — The thermometer should be held vertically and should not be tilted during measurement.
3. Reading method — The temperature must be read while the thermometer is still immersed, with the eye directly in line with the liquid column level.
Conclusion: Following the correct procedure ensures accurate and reliable temperature readings with a laboratory thermometer.

Introduction: The smallest value a laboratory thermometer can read is found by examining the divisions on its scale.
Key Points:
1. Identify bigger marks — Find the temperature difference between two bigger marks on the scale.
2. Count divisions — Count the number of small divisions between those two bigger marks.
3. Calculation example — Between 0 °C and 10 °C there are 10 divisions, so each division reads 10 ÷ 10 = 1 °C.
Conclusion: Dividing the temperature difference between two bigger marks by the number of divisions gives the smallest readable value.

Introduction: A laboratory thermometer is not suitable for measuring human body temperature due to its design and usage method.
Key Points:
1. Different purpose — A laboratory thermometer is designed for measuring temperatures of substances other than the human body.
2. Reading method — It must be read while immersed in the liquid, which is not practical for body temperature measurement.
3. No clinical features — It lacks provisions like placing under the tongue, as available with a clinical thermometer.
Conclusion: The laboratory thermometer's design and reading method make it unsuitable for measuring body temperature.

Introduction: In Activity 7.6, different students in Shillong recorded slightly different temperatures for boiling water.
Key Points:
1. Recorded readings — The temperatures recorded by students ranged from 97.8 °C to 98.1 °C.
2. Slight differences — The readings differed slightly from each other rather than being exactly the same.
3. Possible reason — The correct way of reading the thermometer may not have been followed by all students, such as eye position or reading while immersed.
Conclusion: Differences in thermometer readings arise when the correct reading procedure is not followed consistently.

Introduction: The temperature of water and ice remains constant during boiling and melting respectively.
Key Points:
1. Boiling water — The temperature of water remains constant while it is boiling, even though heat continues to be supplied.
2. Melting ice — The temperature of ice remains constant while it is melting, even as heat is absorbed.
3. Observation — These observations were made by reading the temperatures of ice and boiling water at intervals and finding them unchanged.
Conclusion: During both boiling and melting, the temperature of the substance stays constant until the process is complete.

Introduction: Certain precautions must be followed while using a digital clinical thermometer for safe and accurate measurement.
Key Points:
1. Read instructions — The thermometer should be used after reading the instruction manual provided with it.
2. Wash the tip — The tip should be washed with soap and water before and after use, keeping the display out of water.
3. Proper handling — The thermometer should not be held by the tip; it should be placed under the tongue with the mouth closed until the beep or light appears.
Conclusion: Following these precautions ensures hygiene, accuracy and longevity of the digital clinical thermometer.

Introduction: There are specific rules for writing the names and symbols of temperature units to ensure uniformity.
Key Points:
1. Scale names — Scale names (Celsius, Fahrenheit, Kelvin) start with a capital letter; 'kelvin' starts with a lowercase letter.
2. Symbols — Symbols °C, °F and K use capital letters; no degree sign is written with K; no full stop is used except at sentence end.
3. Spacing and plural — A space is left between the number and the unit, and 'degrees' (plural) is used for temperatures above one degree.
Conclusion: Correct writing of temperature units and symbols ensures clarity and consistency in scientific communication.

Introduction: Temperature in the Kelvin scale is obtained by adding 273.15 to the Celsius scale temperature.
Key Points:
1. Conversion formula — Temperature in Kelvin = Temperature in Celsius + 273.15.
2. Calculations — (i) 40 °C + 273.15 = 313.15 K; (ii) 0 °C + 273.15 = 273.15 K.
3. Third conversion — (iii) 100 °C + 273.15 = 373.15 K.
Conclusion: Using the formula K = °C + 273.15, the three temperatures convert to 313.15 K, 273.15 K and 373.15 K respectively.

Introduction: A laboratory thermometer with a wide range is preferred because laboratory work involves various temperatures.
Key Points:
1. Wide range needed — Laboratory work involves measuring temperatures of ice, boiling water and warm water, which span a wide range.
2. Clinical thermometer limitation — A clinical thermometer has a narrow range of about 35–42 °C, which cannot measure ice or boiling water temperatures.
3. Laboratory thermometer range — A range of –10 °C to 110 °C covers ice, room temperature and boiling water, making it suitable for laboratory use.
Conclusion: The wide range of the laboratory thermometer makes it more suitable for laboratory work than a clinical thermometer.

Introduction: Two friends may get different readings of the same warm water if the correct measurement method is not followed.
Key Points:
1. Bulb touching bottom or sides — If the bulb touches the bottom or sides of the beaker, the reading will be incorrect.
2. Tilting the thermometer — If the thermometer is held tilted instead of vertically, the reading may differ.
3. Reading after removal or wrong eye position — If the reading is taken after removing the thermometer or if the eye is not in line with the liquid column, the readings will differ.
Conclusion: Incorrect measurement techniques lead to differences in temperature readings of the same warm water.

Introduction: Anna Mani, known as the 'Weather Woman of India', made significant contributions to science and renewable energy.
Key Points:
1. Weather instruments — She invented and built a large number of weather measurement instruments, reducing India's reliance on other nations.
2. Renewable energy — She explored the possibilities of using wind and solar energy in India.
3. Global leadership — Her work helped India become one of the global leaders in renewable energy.
Conclusion: Anna Mani's contributions in weather instrumentation and renewable energy advanced India's scientific self-reliance.

Introduction: Air temperature is an important weather parameter measured using thermometers at weather stations worldwide.
Key Points:
1. Measurement — Air temperature is measured using thermometers and monitored at weather stations all over the world.
2. Weather forecasts — The data gathered on air temperature along with other parameters is used for making weather forecasts.
3. Seasonal variation — Maximum and minimum air temperatures vary daily, rising towards summer and falling in winter.
Conclusion: Air temperature measurement is essential for weather forecasting and understanding seasonal climate patterns.

Introduction: The smallest value a thermometer can read is calculated from the divisions between two bigger marks.
Key Points:
1. Temperature difference — The difference between the two bigger marks 10 °C and 20 °C is 10 °C.
2. Number of divisions — There are 20 divisions between these two bigger marks.
3. Calculation — Smallest value = 10 °C ÷ 20 = 0.5 °C.
Conclusion: The smallest value that this laboratory thermometer can read is 0.5 °C.

Hint: (a) Digital clinical thermometer — measures human body temperature; (b) For hygiene and to remove germs before and after use; (c) No — our sense of touch is not always reliable for judging hotness/coldness, so a thermometer is needed for correct measurement.

Hint: (a) Cool; (b) Warm; (c) The same water feels different to the two hands — we cannot always rely upon our sense of touch to decide whether a body is hot or cold; a thermometer gives a reliable measure.

Hint: (a) 40.0 °C on Day 1 at 7 pm; (b) Day 3; (c) Age, time of the day, or activity level.

Hint: (a) Student 3; (b) Student 1 tilted the thermometer, Student 2 let the bulb touch the bottom, Student 4 read after removing the thermometer; (c) The bottom/sides may be at a different temperature than the water, giving a wrong reading.

Hint: (a) To keep it in proper contact with the body for an accurate reading; (b) The thermometer makes a beeping sound or flashes a light; (c) Wash the tip with soap and water; keep the digital display portion out of water.

Hint: (a) Non-contact or infrared thermometers — they measure temperature without touching a person's body; (b) They reduce the risk of spreading disease; (c) Fever (temperature above normal) indicates illness, and the body temperature does not normally go beyond 42 °C.

Hint: (a) The lowest to the highest temperature it can measure; (b) Difference = 10 °C over 10 divisions, so 10/10 = 1 °C; (c) Different thermometers may have different ranges and smallest division values.

Hint: (a) Fahrenheit scale; (b) 98.6 °F; (c) 37.0 °C on the Celsius scale equals 98.6 °F on the Fahrenheit scale — Komal's 101 °F is a few degrees above normal, indicating fever.

Hint: (a) The 'Weather Woman of India'; (b) Her instruments reduced India's reliance on other nations for such instruments; (c) Renewable energy — she explored the possibilities of using wind and solar energy in India.

Hint: (a) No — normal temperature is the average of a large number of healthy people; a healthy person may differ slightly from 37.0 °C; (b) Age, time of the day, activity level; (c) Not below 35 °C and not above 42 °C.

Introduction: Temperature is a reliable measure of the hotness or coldness of a body, measured using different scales.
Key Points:
1. Definition of temperature — Temperature is a reliable measure of hotness or coldness; a hotter body has a higher temperature than a colder one.
2. Celsius scale — The unit is degree Celsius, denoted by °C; it is commonly used in clinical thermometers.
3. Fahrenheit scale — The unit is degree Fahrenheit, denoted by °F; 37.0 °C equals 98.6 °F on this scale, but it is not used in most scientific studies anymore.
4. Kelvin scale — The unit is kelvin, denoted by K; it is the SI unit of temperature and no degree sign is used with K.
5. Celsius–Kelvin conversion — Temperature in Kelvin = Temperature in Celsius + 273.15; for example, 37 °C = 37 + 273.15 = 310.15 K.
Conclusion: Temperature is measured on three scales — Celsius, Fahrenheit and Kelvin — with Kelvin being the SI unit, and conversion between Celsius and Kelvin uses a simple addition formula.

Introduction: A digital clinical thermometer is a battery-operated device used to measure human body temperature accurately.
Key Points:
1. Description and working — It shows temperature digitally, runs on batteries and uses heat sensors to determine temperature when placed in contact with the body.
2. Measurement method — Wash hands and tip, reset the thermometer, place it under the tongue with mouth closed, wait for the beep or light, then read the display.
3. Cleaning after use — After reading, clean the tip with soap and water and dry it before storing.
4. Precaution — instruction manual — Always use the thermometer after reading the instruction manual provided with it.
5. Precaution — washing and handling — Wash the tip before and after use, keep the display out of water, and do not hold the thermometer by the tip.
Conclusion: A digital clinical thermometer provides safe, accurate body temperature readings when used correctly with proper precautions.

Introduction: Mercury thermometers were replaced by digital thermometers due to the risks associated with mercury and the advantages of digital technology.
Key Points:
1. Toxicity of mercury — Mercury is an extremely toxic substance that is difficult to dispose of if the thermometer breaks accidentally.
2. No such risk with digital — Digital thermometers pose no risk of toxic mercury exposure, making them safer to use.
3. Easier to read — The digital display in digital thermometers is easier to read compared to the liquid column in mercury thermometers.
4. Heat sensor technology — Temperature in a digital thermometer is determined with the help of heat sensors, providing accurate readings.
5. Battery operated — Digital thermometers run on batteries, making them convenient and portable for home and clinical use.
Conclusion: Digital thermometers replaced mercury thermometers because they are safer, easier to read and equally accurate.

Introduction: A laboratory thermometer is a device used to measure the temperature of substances other than the human body.
Key Points:
1. Structure — It consists of a long, narrow, uniform sealed glass tube with a bulb at one end containing alcohol (coloured red) or mercury.
2. Scale and liquid column — A Celsius scale is marked along the tube; the liquid column rises or falls with change in temperature, and the mark coinciding with the top of the column gives the reading.
3. Finding the range — The range is the lowest to the highest temperature the thermometer can measure, usually –10 °C to 110 °C.
4. Finding smallest value — Find the temperature difference between two bigger marks and divide by the number of divisions between them.
5. Example — Between 0 °C and 10 °C there are 10 divisions, so each small division reads 10 ÷ 10 = 1 °C, which is the smallest value it can read.
Conclusion: A laboratory thermometer has a glass tube with a bulb and a Celsius scale, and its range and smallest readable value are determined by examining the scale markings.

Introduction: Accurate temperature measurement with a laboratory thermometer requires following the correct method and precautions.
Key Points:
1. Bulb immersion — The bulb should be immersed in the liquid without touching the bottom or sides of the beaker.
2. Vertical holding — The thermometer should be held vertically and should not be tilted during measurement.
3. Read while immersed — The temperature must be read while the thermometer is still immersed in the liquid, as the column falls once removed.
4. Eye position — While reading, the eye should be directly in line with the level of the liquid column to avoid errors.
5. Precautions — Handle the thermometer with care as it can break if it hits a hard object, and do not hold it by the bulb.
Conclusion: Correct placement, vertical holding, reading while immersed and proper eye alignment ensure accurate temperature measurement safely.

Introduction: The sense of touch cannot always correctly judge whether a body is hot or cold, as demonstrated by a simple activity.
Key Points:
1. Setup of containers — Three containers were taken: A with warm water, B with tap water and C with ice-cold water.
2. Dipping hands — The right hand was dipped in container A and the left hand in container C for 1–2 minutes.
3. Placing both hands in B — Both hands were then placed simultaneously in container B (tap water).
4. Conflicting sensations — The right hand felt B as cool while the left hand felt the same water B as warm.
5. Inference — The same water giving two different sensations proves that we cannot always rely on our sense of touch to measure hotness or coldness; hence a thermometer is needed.
Conclusion: The three-container activity demonstrates that the sense of touch is unreliable for measuring temperature, making thermometers necessary.

Introduction: Body temperature is an important health indicator, and its measurement varies with age and other factors.
Key Points:
1. Normal body temperature — The normal temperature of a healthy human body is 37.0 °C (98.6 °F), which is the average of a large number of healthy people.
2. Variation from normal — A perfectly healthy person may have a temperature slightly different from 37.0 °C; it normally does not go below 35 °C or above 42 °C.
3. Factors affecting temperature — Body temperature is influenced by age, time of the day and activity level.
4. Measuring small children's temperature — For small children or old people, the thermometer can be placed in the armpit instead of under the tongue.
5. Armpit reading adjustment — The temperature measured in the armpit is about 0.5 °C to 1 °C lower than the actual body temperature.
Conclusion: Normal body temperature is 37.0 °C but varies with age, time and activity, and armpit readings for children need adjustment.

Introduction: Air temperature is an important weather parameter that is measured and monitored worldwide for forecasting.
Key Points:
1. Measurement — Wall thermometers give an approximate idea of room temperature; air temperature is monitored at weather stations all over the world.
2. Weather forecasts — The data gathered on air temperature along with other parameters is used for making weather forecasts.
3. Seasonal changes — Maximum and minimum air temperatures vary daily, rising as summer approaches and falling during winter.
4. Anna Mani's instruments — Anna Mani, the 'Weather Woman of India', invented and built a large number of weather measurement instruments, reducing India's reliance on other nations.
5. Renewable energy work — She explored wind and solar energy possibilities in India, helping India become a global leader in renewable energy.
Conclusion: Air temperature measurement is crucial for weather forecasting, and Anna Mani's contributions advanced India's capabilities in both weather instrumentation and renewable energy.

Introduction: There are specific rules for writing the names and symbols of temperature units to maintain scientific uniformity.
Key Points:
1. Scale names capitalised — The names of temperature scales — Celsius, Fahrenheit and Kelvin — start with a capital letter.
2. Degree and kelvin — In 'degree Celsius' and 'degree Fahrenheit', 'degree' starts with a lowercase letter while Celsius and Fahrenheit are capital; 'kelvin' starts with a lowercase letter.
3. Symbols — The symbols °C, °F and K are all capital letters; note that the degree sign is not written with K.
4. No full stop — A full stop is not written after the symbol except at the end of a sentence, and a space is left between the number and the unit.
5. Plural form — For temperatures more than one degree, the plural 'degrees' is used when writing the full form of the unit.
Conclusion: Following these rules for names and symbols ensures clarity and consistency in writing temperature values across scientific work.

Introduction: Non-contact thermometers measure temperature without touching the body, while clinical thermometers have a limited range of measurement.
Key Points:
1. Non-contact thermometers — These are also called infrared thermometers; they measure temperature without touching a person's body using infrared sensing.
2. Advantage — They reduce the risk of spreading disease, as there is no physical contact with the person.
3. COVID-19 importance — During the COVID-19 pandemic, these thermometers were widely used to check temperatures safely without transmission risk.
4. Clinical thermometer range — A clinical thermometer has a limited range of roughly 35–42 °C, suitable only for body temperature.
5. Cannot measure boiling water or ice — Boiling water (around 100 °C) and ice (0 °C and below) fall outside the clinical thermometer's range, so a laboratory thermometer is needed for such measurements.
Conclusion: Non-contact thermometers became vital during COVID-19 for safe temperature screening, while clinical thermometers are limited to body temperature range only.