Class 7 Science – Heat: Easy Notes & Questions Answers (MCQ, Very Short, Short, Long)
This post covers the complete study material for Class 7 Science – Heat in one place. You’ll find easy, exam-focused notes and a full set of questions and answers designed for quick revision and strong concept building. Use the jump buttons to go directly to the section you need. All content follows a student-friendly tone, with clear examples and everyday applications to make learning smooth and efficient.
📘 Notes: Heat (Class 7 Science)
1) What is Heat? What is Temperature?
Heat is a form of energy that flows from a hotter object to a cooler object when they are in contact or connected through a path for transfer. Temperature is a measure of the degree of hotness or coldness of a body. When two bodies at different temperatures touch, heat flows from the body at a higher temperature to the one at a lower temperature until both reach the same temperature (thermal equilibrium).
2) Measuring Temperature: Thermometers
A thermometer is used to measure temperature. Common types you meet in Class 7 are:
- Clinical thermometer: Measures human body temperature (roughly 35°C to 42°C). Normal body temperature is about 37°C (98.6°F).
- Laboratory thermometer: Used for experiments; has a wider range than clinical thermometers.
Most conventional thermometers used in textbooks work with mercury (or colored alcohol) that expands when heated and contracts on cooling, moving along a calibrated glass scale.
3) Modes of Heat Transfer
Heat moves in three main ways. Understanding these helps you explain many daily-life observations.
- Conduction: Heat transfer through solids without the actual movement of particles at the macroscopic level. When one end of a metal spoon is placed in a hot liquid, the other end becomes warm due to conduction. Metals are typically good conductors; wood and plastic are poor conductors (insulators).
- Convection: Heat transfer in liquids and gases (fluids) due to the movement of warmer, less dense regions and cooler, denser regions. When water is heated from below, the hot water rises and cooler water sinks, forming convection currents.
- Radiation: Transfer of heat in the form of waves that do not require any medium. Heat from the Sun reaches Earth by radiation. Dark, dull surfaces absorb radiation better; shiny, light surfaces reflect more.
4) Conductors and Insulators
Conductors (e.g., copper, aluminum, iron) allow heat to pass through quickly. Insulators (e.g., wood, plastic, cork, wool) restrict the flow of heat. That’s why cooking pans are metal but handles are often plastic or wood.
5) Land Breeze and Sea Breeze
The different heating and cooling rates of land and water cause local winds near coasts:
- Sea Breeze (daytime): Land heats faster; warm air over land rises; cooler air from sea moves toward land.
- Land Breeze (night): Land cools faster; relatively warmer air lies above sea; cooler air from land flows toward sea.
6) Choice of Clothing in Different Seasons
In winter, woolen clothes keep us comfortable because wool traps a lot of air within its fibers, and air is a poor conductor of heat. In summer, cotton is preferred because it absorbs sweat and allows better air circulation, helping the body feel cooler.
7) Everyday Applications of Heat Concepts
- Cooking utensils: Metals (good conductors) for pots; insulated handles for safe grip.
- Thermos flasks: Minimize heat loss by combining insulation and reflective surfaces to reduce conduction, convection, and radiation.
- Color of roofs and clothing: Light colors reflect more heat in hot regions; darker colors absorb more heat in cold regions.
📝 Questions & Answers: Heat (Class 7 Science)
A) Multiple Choice Questions (MCQ) – Choose the correct option
Q1. Which mode of heat transfer does not require a medium?
a) Conduction b) Convection c) Radiation d) Condensation
Answer: c) Radiation
Q2. The normal human body temperature is about:
a) 32°C b) 37°C c) 42°C d) 27°C
Answer: b) 37°C
Q3. During the day near the sea, air generally moves:
a) From land to sea b) From sea to land c) Only upward d) Only downward
Answer: b) From sea to land
Q4. Which is a good conductor of heat?
a) Wood b) Plastic c) Copper d) Wool
Answer: c) Copper
Q5. Heat travels through solids by:
a) Radiation b) Conduction c) Convection d) Evaporation
Answer: b) Conduction
Q6. A clinical thermometer is designed mainly to measure:
a) Room temperature b) Human body temperature c) Water temperature in a beaker d) Oven temperature
Answer: b) Human body temperature
Q7. Wool keeps us comfortable in winter mainly because it:
a) Is heavy b) Absorbs water c) Traps air (poor conductor) d) Reflects light strongly
Answer: c) Traps air (poor conductor)
B) Very Short Answer Questions (Answer in 1–2 lines)
Q1. Define heat.
Heat is energy that flows from a body at higher temperature to a body at lower temperature.
Q2. What does a thermometer measure?
It measures temperature, i.e., the degree of hotness or coldness.
Q3. Name the three modes of heat transfer.
Conduction, Convection, and Radiation.
Q4. Which type of clothes are comfortable in summer?
Light, breathable cotton clothes.
Q5. Why are utensil handles often plastic?
Plastic is a poor conductor, so handles remain safer to hold.
Q6. What causes sea breeze?
Land heats faster; warm air rises over land; cooler air from sea flows toward land.
Q7. Does radiation need a medium?
No, radiation can travel through vacuum.
C) Short Answer Questions (3–4 sentences)
Q1. Explain conduction with one daily-life example.
Conduction is transfer of heat through a solid from the hot end to the cold end. A metal spoon placed in a hot cup warms up from the immersed end to the handle because heat travels through the metal.
Q2. How does convection heat water in a vessel?
Water nearest the flame gets warm, becomes less dense, and rises. Cooler, denser water moves down to take its place, forming convection currents that distribute heat throughout the vessel.
Q3. Why do we prefer light-colored clothes in hot regions?
Light colors reflect more radiant energy, reducing heat absorption and helping the body feel cooler, especially under strong sunlight.
Q4. State two differences between clinical and laboratory thermometers.
A clinical thermometer measures human body temperature with a narrow range (about 35–42°C) and a constriction to hold the reading. A laboratory thermometer has a wider range, no constriction, and is used for experiments.
Q5. Why are houses in cold regions often painted darker outside?
Darker colors absorb more radiant energy, which can help keep interiors relatively warmer during sunlight hours.
Q6. What is thermal equilibrium?
When two bodies in contact reach the same temperature and there is no net heat flow between them, they are in thermal equilibrium.
Q7. Mention one way a thermos flask reduces heat loss by each mode.
Vacuum reduces conduction and convection; a reflective inner surface reduces radiation.
D) Long Answer Questions (explain in detail)
Q1. Describe the three modes of heat transfer with suitable examples from daily life.
Heat transfers as conduction, convection, and radiation. In conduction, energy passes through solids; for instance, a metal ladle warms along its length in hot soup. In convection, fluids transfer heat by bulk motion; warm air rising near a heater and cooler air descending is a common example, as is water heating in a pan. In radiation, energy travels as waves needing no medium; sunlight warming your skin or a room is radiation. Recognizing the mode helps explain why utensils are metallic, why rooms warm unevenly, and how we receive energy from the Sun.
Q2. Explain sea breeze and land breeze in terms of differential heating of land and water.
Land heats and cools faster than water. During the day, land becomes warmer; air above it expands and rises, so comparatively cooler, denser air from the sea flows toward land—this is sea breeze. At night, land cools faster and becomes cooler than the sea; air above the sea remains relatively warmer, so cooler air from land moves toward the sea—this is land breeze. These local winds are useful in moderating temperatures along coasts and are a direct outcome of convection in air.
Q3. Why do winter clothes often have multiple layers or fluffy textures? Use the concept of conduction to justify.
Multiple layers and fluffy textures trap pockets of air. Air is a poor conductor of heat, so these trapped layers slow down heat loss from the body to the surroundings. Wool fibers, for example, hold air and create an insulating barrier. The reduced conduction through this barrier keeps the body relatively warmer, which is why layered clothing and woolens are preferred in cold weather.
Q4. A cookware set includes a steel pot with a wooden handle and a bright, shiny outer surface. Explain the science behind each design choice.
The steel pot conducts heat efficiently to cook food. The wooden handle is used because wood is a poor conductor, so it remains safer to hold compared to metal. A bright, shiny outer surface reflects a portion of radiant heat, reducing heat loss by radiation from the pot’s exterior. Together, these choices improve safety and energy efficiency while maintaining cooking performance.
Q5. Compare conduction in metals with convection in fluids using a clear example for each and state how they influence our daily choices.
In metals, conduction dominates: energy passes from hot regions to cooler ones along the solid lattice; hence metallic pans heat uniformly and quickly. In fluids, convection is key: as water at the bottom of a pot warms, it rises while cooler water sinks, circulating heat. These principles guide everyday choices—metals for cookware to speed cooking, plastic or wooden handles for safety, and ventilation designs in rooms to promote comfortable air circulation.
Q6. What precautions should be taken while using a clinical thermometer and how is the reading noted?
Before use, ensure the mercury level is below the minimum scale mark by gently flicking. Place the bulb under the tongue or in the armpit as recommended and wait the advised time. Remove, hold at eye level, and read the mercury column against the scale. Clean the thermometer appropriately after use. These steps ensure accurate and hygienic measurement of body temperature.
Q7. A room has a heater near the floor and a ventilator near the ceiling. Explain how this arrangement supports comfortable conditions using convection and radiation ideas.
The heater warms air near the floor; this air expands and rises, carrying heat upward (convection). Cooler air descends to replace it, creating circulation that spreads warmth through the room. A ventilator near the ceiling lets out overly warm or stale air. Any radiant heat from the heater directly warms nearby objects and people. Together, these effects improve comfort and air quality.
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