All questions of Temperature & its Measurement for JAMB Exam

Infrared thermometers allowed temperature measurements without physical contact, reducing the risk of virus transmission.

Liquid Used in Laboratory Thermometers
In laboratory thermometers, the most commonly used liquid is mercury. Here’s why:
1. High Thermal Conductivity
- Mercury has excellent thermal conductivity, allowing it to respond quickly to temperature changes.
- This characteristic ensures accurate readings within a short span of time.
2. Wide Temperature Range
- Mercury remains in a liquid state over a wide range of temperatures, typically from -39°C to 356°C.
- This makes it suitable for measuring various temperatures in laboratory settings.
3. Visibility
- Mercury forms a distinct meniscus, making it easy to read the scale on the thermometer.
- Its shiny appearance enhances visibility, allowing for precise measurements.
4. Non-Wetting Property
- Mercury does not wet glass, which prevents it from clinging to the sides of the thermometer.
- This property helps in obtaining accurate readings without any residue affecting the measurement.
5. Stability and Reliability
- Mercury is stable and does not evaporate easily at room temperature, ensuring consistent performance.
- This reliability is crucial in scientific experiments where precision is key.
Conclusion
While other liquids like water, oil, and alcohol are used in thermometers, mercury is preferred for laboratory use due to its superior properties. Its ability to provide quick, accurate, and reliable temperature readings makes it an essential tool in scientific research.

A clinical thermometer is designed for measuring human body temperature in Celsius (°C) or Fahrenheit (°F).

The Kelvin (K) scale is commonly used in science because it starts at absolute zero.

Heat always flows from a hotter object to a colder one until both objects reach thermal equilibrium.

Understanding Temperature Conversion
When converting temperature from Celsius to Kelvin, the key is to understand the relationship between these two scales. Kelvin is an absolute temperature scale, where 0 K (zero Kelvin) is equivalent to -273.15°C, the point at which all molecular motion stops.
Why Add 273.15?
- The Kelvin scale starts at absolute zero, while the Celsius scale starts at the freezing point of water (0°C).
- To convert Celsius to Kelvin, you need to shift the scale upwards by the amount of degrees that represent absolute zero.
- Since 0°C corresponds to 273.15 K, you simply add 273.15 to the Celsius temperature.
Conversion Formula
- The formula to convert Celsius (C) to Kelvin (K) is:
K = C + 273.15
Example of Conversion
- If you have a temperature of 25°C:
K = 25 + 273.15 = 298.15 K
- This shows how you shift from the Celsius scale to the Kelvin scale.
Why Other Options Are Incorrect
- Option a: Multiply by 2 does not account for the absolute zero and does not provide any meaningful conversion.
- Option c: Subtracting 273.15 would actually give a negative Kelvin value, which is not possible.
- Option d: Dividing by 2 also fails to provide the correct relationship between the two temperature scales.
In conclusion, the correct method to convert Celsius to Kelvin is to add 273.15 to the Celsius temperature, making option B the right answer.

Secondary Standard Temperature Scale
Celsius, Fahrenheit, and Rankine are all examples of primary temperature scales. However, the Kelvin scale is an example of a secondary standard temperature scale.

Explanation:
- Celsius: The Celsius scale is based on the freezing and boiling points of water, where 0 degrees Celsius is the freezing point and 100 degrees Celsius is the boiling point at standard atmospheric pressure.
- Fahrenheit: The Fahrenheit scale is based on a system where 32 degrees Fahrenheit is the freezing point of water and 212 degrees Fahrenheit is the boiling point of water at standard atmospheric pressure.
- Rankine: The Rankine scale is similar to the Fahrenheit scale but uses absolute zero as its starting point, with 0 degrees Rankine being absolute zero.
- Kelvin: The Kelvin scale is the primary temperature scale used in scientific measurements as it is based on absolute zero, the theoretical lowest possible temperature where all molecular motion ceases.

Significance of Kelvin as a Secondary Standard Temperature Scale:
- The Kelvin scale is often used in scientific research and engineering applications where precise temperature measurements are required.
- It is based on the fundamental properties of matter at the atomic level, making it a more reliable and consistent standard for temperature measurements.
- The Kelvin scale is also used in the field of thermodynamics, where absolute temperatures are essential for calculations and analysis.
In conclusion, the Kelvin scale is an example of a secondary standard temperature scale due to its reliance on absolute zero and its widespread use in scientific and engineering disciplines.

Anna Mani was an Indian scientist who developed weather measurement tools and reduced the need for imported equipment.

Function of a Capillary Tube in a Laboratory Thermometer
A laboratory thermometer is a precision instrument designed to measure temperature, and the capillary tube plays a crucial role in its functionality.
Understanding the Capillary Tube
- The capillary tube is a narrow, elongated glass tube that is connected to the bulb containing the liquid (usually mercury or colored alcohol).
- Its size is specifically designed to allow easy movement of the liquid inside.
Liquid Column Expansion
- When the temperature increases, the liquid in the bulb expands due to thermal energy.
- This expansion causes the liquid to rise through the capillary tube.
- The narrow diameter of the tube ensures that even small changes in temperature result in noticeable movement of the liquid column.
Visible Temperature Changes
- The scale marked on the thermometer is directly aligned with the capillary tube.
- As the liquid rises, it aligns with the scale, allowing for accurate temperature readings.
- The design ensures that the liquid's movement is smooth and responsive, facilitating quick and precise measurement.
Conclusion
In summary, the capillary tube in a laboratory thermometer is essential for allowing the liquid column to expand and accurately show temperature changes. Its narrow structure ensures that even minor temperature fluctuations can be detected, making it a vital component for precise temperature measurement in laboratory settings.

Mercury is a toxic substance, making mercury thermometers hazardous. Digital thermometers are safer and more convenient.

Temperature indicates how much heat energy an object has, determining whether it is hot or cold.

- The Kelvin (K) is the standard SI unit for measuring temperature.
- It is commonly used in scientific contexts because it starts at absolute zero, the point where all molecular motion stops.
- Unlike Celsius and Fahrenheit, which are based on specific temperature points (like the freezing and boiling of water), Kelvin provides a direct measure of thermal energy.
- Therefore, for precise scientific calculations and experiments, Kelvin is the preferred unit.

Different materials conduct heat differently, which can trick our sense of touch into perceiving incorrect temperatures.

Laboratory thermometers are used in scientific experiments to measure the temperature of liquids, gases, or solids.

A thermometer is specifically designed to measure temperature accurately.

The normal body temperature of a healthy adult is around 37°C or 98.6°F.