Answer key

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Last edited 26 days ago by Learn LoopHQ.

Chapter: 03. Physical Quantities And Measurement 2

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Answer Key - Physical Quantities and Measurement - 2: Practice Exam Paper

Section A: Multiple Choice Questions (5 Marks)

c) second

c) 35° C to 42° C

c) Ensure the mercury level stays after taking the reading.

d) Atomic clock

b) Stopwatch

Section B: Fill in the Blanks (5 Marks)

interval

rotation

hotness

37° C

higher, lower

Section C: True or False (5 Marks)

Section D: Short Answer Questions (10 Marks)

Measuring temperature is essential in daily life to understand how hot or cold things are, helping us assess health (like fever), manage food safety, and understand weather conditions.

The 24-hour clock format is preferred in some professions (like aviation or military) because it avoids any confusion between a.m. and p.m. times, ensuring clear and unambiguous communication.

Parallax error occurs when reading a thermometer if your eye is not directly in line with the top of the mercury column, leading to an inaccurate reading.

You can tell if a person has a fever if their body temperature reading on a clinical thermometer is above the normal 37° C or 98.6° F.

One advantage of using a digital thermometer is that it does not contain mercury, making it safer for home use and environmentally friendlier upon disposal if it breaks.

Section E: Diagram-Based Questions (5 Marks)

The part labeled ‘Constriction’ is the narrow kink or bend located just above the bulb of the thermometer.

The main function of the constriction is to prevent the mercury from falling back into the bulb immediately after the thermometer is removed from the body, allowing time to read the temperature accurately.

Based on the presence of the ‘Constriction’, the thermometer most likely represented in this diagram is a clinical thermometer.

Section F: Long Answer Questions (10 Marks)

A laboratory thermometer and a clinical thermometer differ in their purpose, range, and construction. A laboratory thermometer is used for measuring temperatures of various substances in experiments, having a wide range (e.g., -10°C to 110°C) and no constriction, so mercury falls quickly. In contrast, a clinical thermometer is designed specifically for human body temperature, with a narrow range (e.g., 35°C to 42°C), and importantly, it has a constriction (kink) to hold the mercury level for an accurate reading after removal from the patient.

Heat and temperature are related but distinct physical quantities. Temperature is the degree of hotness or coldness of a body, reflecting the average kinetic energy of its particles. Heat, on the other hand, is a form of energy that is transferred from one body to another due to a temperature difference. Heat transfer always occurs from a body at a higher temperature to a body at a lower temperature until both bodies reach the same temperature. While heat causes changes in temperature, a body’s temperature alone doesn’t tell you the total heat energy it contains, as heat also depends on factors like the amount of substance.

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