CBSE Class 7 Science Chapter 4 Heat NCERT Solutions

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NCERT Solutions PDF Class 7 PDF

This chapter delves into the fundamental concepts of heat and temperature for CBSE Class 7 Science students. It explains how to differentiate between heat and temperature, and introduces various types of thermometers, including clinical and laboratory thermometers, highlighting their similarities and differences. The solutions also cover the three main modes of heat transfer: conduction, convection, and radiation, providing examples for each. Additionally, students will learn about conductors and insulators of heat, and the role of clothing color and layers in regulating body temperature during different seasons. These NCERT Solutions are designed to provide clear, step-by-step explanations to help students understand complex topics and prepare effectively for their exams.

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Quick info

BoardCBSE
ClassClass 7
SubjectScience
Session2026
LanguageEnglish
TypeNCERT Solutions
ChapterChapter 4

Chapter summary

Chapter 4 of the CBSE Class 7 Science curriculum focuses on 'Heat'. This section provides NCERT Solutions that clarify the concepts of temperature measurement using clinical and laboratory thermometers, detailing their distinctions and commonalities. It also explains the processes of heat transfer (conduction, convection, radiation) and differentiates between conductors and insulators. The chapter concludes with practical applications, such as understanding why layered clothing keeps us warmer in winter and the effect of clothing color on heat absorption. These solutions aim to build a strong foundation in thermal concepts.

Learning outcomes

  • Understand the difference between heat and temperature.
  • Identify similarities and differences between clinical and laboratory thermometers.
  • Explain the processes of conduction, convection, and radiation.
  • Differentiate between conductors and insulators of heat.
  • Explain the role of clothing in regulating body temperature.

Topics covered

Paper topics

  • Heat and Temperature
  • Thermometers
  • Clinical Thermometer
  • Laboratory Thermometer
  • Heat Transfer
  • Conduction
  • Convection
  • Radiation
  • Conductors
  • Insulators
  • Effect of Clothing Color
  • Layered Clothing in Winter

Important topics

  • Thermometer Types and Differences
  • Modes of Heat Transfer (Conduction, Convection, Radiation)
  • Conductors vs. Insulators
  • Application of Heat Transfer Concepts

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Questions and Solutions

Question 1

State the similarities and differences between the laboratory thermometer and the clinical thermometer.
Solution: Both clinical and laboratory thermometers are instruments used to measure temperature and work on the same fundamental principle of thermal expansion of mercury. They both consist of a glass tube with a fine capillary and a bulb at one end containing mercury. Markings in degrees Celsius and Fahrenheit are present on both.

However, they have key differences:

  • Usage: A clinical thermometer is specifically designed to measure human body temperature, while a laboratory thermometer is used for measuring temperatures in experiments and industrial settings.
  • Temperature Range: A clinical thermometer typically ranges from 35°C to 42°C, covering the normal human body temperature range. A laboratory thermometer has a much wider range, usually from -10°C to 110°C.
  • Constriction: Clinical thermometers have a kink or constriction near the bulb, which prevents the mercury level from falling back after removal from the body, allowing for an accurate reading. Laboratory thermometers do not have this constriction.
  • Handling: A clinical thermometer can be tilted to read the temperature, whereas a laboratory thermometer must be kept upright for accurate measurement.

Question 2

Give two examples each of conductors and insulators of heat.
Solution:

Conductors of heat are materials that allow heat to pass through them easily. Examples include:

  • Copper
  • Aluminum
  • Iron

Insulators of heat are materials that do not allow heat to pass through them easily. Examples include:

  • Wood
  • Water
  • Air

Question 3

Fill in the blanks:
  1. The hotness of an object is determined by its _____.
  2. Temperature of boiling water cannot be measured by a _____ thermometer.
  3. Temperature is measured in degree _____.
  4. No medium is required for transfer of heat by the process of ______.
  5. A cold steel spoon is dipped in a cup of hot milk. It transfers heat to its other end by the process of ______.
  6. Clothes of _____ colours absorb heat better than clothes of light colours.
Solution:
  1. The hotness of an object is determined by its temperature.
  2. Temperature of boiling water cannot be measured by a clinical thermometer.
  3. Temperature is measured in degree Celsius.
  4. No medium is required for transfer of heat by the process of radiation.
  5. A cold steel spoon is dipped in a cup of hot milk. It transfers heat to its other end by the process of conduction.
  6. Clothes of dark colours absorb heat better than clothes of light colours.

Question 4

Match the following:
  1. Land breeze blows during (a) summer
  2. Sea breeze blows during (b) winter
  3. Dark coloured clothes are preferred during (c) day
  4. Light coloured clothes are preferred during (d) night
Solution:
  1. Land breeze blows during (d) night
  2. Sea breeze blows during (c) day
  3. Dark coloured clothes are preferred during (b) winter
  4. Light coloured clothes are preferred during (a) summer

Question 5

Discuss why wearing more layers of clothing during winter keeps us warmer than wearing just one thick piece of clothing.
Solution: Wearing multiple layers of clothing in winter helps us stay warmer because air gets trapped between the layers. Air is a poor conductor of heat (an insulator). This trapped air acts as a barrier, preventing our body heat from escaping into the colder surroundings. Each additional layer with trapped air increases the insulation effect. Therefore, several thin layers provide better warmth than a single thick layer because they trap more air.

Common mistakes

  • Confusing heat and temperature.
  • Not understanding the specific temperature ranges for different thermometers.
  • Misidentifying the mode of heat transfer in given scenarios.
  • Incorrectly classifying materials as conductors or insulators.

Revision tips

  • Review the specific temperature ranges and uses of clinical and laboratory thermometers.
  • Memorize the definitions and examples of conduction, convection, and radiation.
  • Understand the practical applications of heat transfer concepts, like clothing choices.
  • Practice identifying conductors and insulators in everyday objects.

Practice MCQs

Q1. What is the primary function of a clinical thermometer?

Q2. Which process of heat transfer does NOT require a medium?

Q3. Which of the following is a good conductor of heat?

Q4. Why do we prefer wearing dark-colored clothes in winter?

Q5. What is the purpose of the constriction in a clinical thermometer?

Frequently asked questions

What is the main difference between a clinical and a laboratory thermometer?

A clinical thermometer measures human body temperature (35°C to 42°C) and has a constriction. A laboratory thermometer measures a wider range of temperatures (-10°C to 110°C) and lacks a constriction.

How is heat transferred through solids?

Heat is primarily transferred through solids by conduction, where particles vibrate and pass energy to adjacent particles.

Can a clinical thermometer measure the temperature of boiling water?

No, a clinical thermometer cannot measure the temperature of boiling water because its range is too narrow (35°C to 42°C), and boiling water is much hotter.

Why are dark clothes better in winter?

Dark clothes absorb more heat from the surroundings compared to light-colored clothes, helping to keep the body warmer in cold weather.

What is the role of air trapped between layers of clothing in winter?

Air trapped between layers of clothing acts as an insulator, preventing body heat from escaping and keeping us warmer.

Which process transfers heat from the Sun to the Earth?

Heat from the Sun travels to the Earth through radiation, as it can travel through the vacuum of space.

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