TNPSC Physics – Heat and Temperature Quiz 2

TNPSC Physics – Heat and Temperature Quiz (Concept Booster)

Understanding heat and temperature concepts is essential for solving TNPSC Physics MCQ questions. This section explains key ideas like heat transfer, temperature scales and thermal properties using simple explanations and real-life examples to help you revise quickly.

This TNPSC Physics Heat and Temperature Quiz helps you practice important concepts effectively.

Q1. Which of the following measures the degree of hotness or coldness of a body?

The degree of hotness or coldness of a body is measured by temperature. It is a physical quantity that indicates how hot or cold an object is. Scientifically, temperature represents the average kinetic energy of particles in a substance.

When particles move faster, the temperature is higher, and when they move slower, the temperature is lower. A thermometer is used to measure temperature in units like Celsius (°C) or Kelvin (K).

Key Points:

• Temperature ≠ Heat (heat is energy, temperature is measure)
• Higher temperature → faster particle motion
• Measured using thermometer
• SI unit: Kelvin (K)

Answer: Temperature

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🔹 Q2. In which direction does heat flow naturally?

Heat always flows from a region of higher temperature to lower temperature. This flow continues until both objects reach the same temperature, which is called thermal equilibrium.

This natural direction of heat flow does not require any external force. It happens due to the difference in temperature between two bodies.

Example:
When you pour hot tea into a cup, it gradually cools down because heat flows from the tea to the surrounding air.

Key Points:

• Heat flows from hot → cold
• Stops at thermal equilibrium
• Based on temperature difference
• No external energy required

Answer: From higher temperature to lower temperature

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Q3. Which of the following substances expands the most when heated?

Explanation:
When substances are heated, their particles gain energy and move farther apart, causing expansion. Among solids, liquids, and gases, gases expand the most because their particles are already far apart and free to move.

Solids have tightly packed particles, so expansion is minimal. Liquids expand more than solids but less than gases.

Key Points:

• Heating increases particle motion
• Expansion order: Gas > Liquid > Solid
• Gases expand maximum due to weak intermolecular forces

Answer: Gas

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🔹 Q4. What happens to the volume of a gas when temperature increases?

Explanation:
When temperature increases, gas particles move faster and require more space. As a result, the volume of the gas increases. This relationship is explained by Charles’ Law, which states that volume is directly proportional to temperature (at constant pressure).

Key Points:

• Increase in temperature → increase in volume
• Based on Charles’ Law
• Faster particle motion requires more space

Answer: Increases

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🔹 Q5. Which of the following is NOT a mode of heat transfer?

Explanation:
Heat transfer occurs through only three methods: conduction, convection, and radiation. Any other option given in the question (like reflection or transmission) is not a mode of heat transfer.

Key Points:

• Conduction → solids
• Convection → liquids & gases
• Radiation → no medium needed
• Reflection → not a method of heat transfer

Answer: Reflection

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🔹 Q6. Why are cooking utensils made of metals?

Explanation:
Metals are good conductors of heat, meaning they allow heat to pass through them quickly. This helps in cooking food evenly and efficiently.

Key Points:

• Metals transfer heat quickly
• Ensures uniform cooking
• Examples: Aluminium, Copper

Answer: Because they are good conductors of heat

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🔹 Q7. The transfer of heat by movement of particles in fluids is called

Explanation:
In liquids and gases, heat is transferred by the movement of particles. Hot particles rise and cold particles sink, creating a circulation. This process is called convection.

Key Points:

• Occurs in fluids (liquids & gases)
• Involves actual movement of particles
• Forms convection currents

Answer: Convection

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🔹 Q8. Which of the following has the lowest temperature?

Explanation:
To compare temperatures given in different units, we must convert them into the same scale. Here, converting all values to Celsius makes comparison easier.

• 0°C = 0°C
• 273 K = 0°C
• 100 K = −173°C
• −50°C = −50°C

Among these values, −173°C is the lowest temperature. Therefore, 100 K corresponds to the lowest temperature.

Key Points:

• Always convert to same unit (Celsius/Kelvin)
• Lower value → lower temperature
• Kelvin to Celsius: subtract 273
• 100 K is much lower than freezing point

Answer: 100 K

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🔹 Q9. What is the boiling point of water in Kelvin?

Explanation:
The boiling point of water is 100°C. To convert Celsius to Kelvin, we use the formula:

K = °C + 273

So, 100 + 273 = 373 K

Key Points:

• Boiling point = 100°C
• Kelvin conversion required
• SI unit is Kelvin

Answer: 373 K

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🔹 Q10. Which material is used as an insulator in cooking utensils?

Explanation:
Insulators are materials that do not allow heat to pass easily. Materials like wood and plastic are used as handles in utensils to prevent burns.

Key Points:

• Insulators block heat transfer
• Used for safety
• Examples: Wood, Plastic

Answer: Wood / Plastic

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🔹 Q11. Why do we feel cool under a fan?

Explanation:
A fan increases the movement of air around our body. This moving air removes heat from the body by convection. At the same time, it also speeds up the evaporation of sweat, which further cools the body.

So, the cooling effect is mainly due to heat being carried away by moving air (convection), along with evaporation.

Key Points:

• Fan does not reduce room temperature
• Moving air removes heat (convection)
• Increases evaporation of sweat
• Cooling happens due to heat loss from body

Answer: Heat is removed by convection

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🔹 Q12. Which process causes cooling of water in an earthen pot?

Explanation:
Water seeps through tiny pores in the earthen pot and evaporates. During evaporation, heat is absorbed from the water, causing cooling.

Key Points:

• Evaporation causes cooling
• Heat is absorbed from water
• Natural cooling method

Answer: Evaporation

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🔹 Q13. The SI unit of temperature is based on

Explanation:
The SI unit of temperature is Kelvin, and it is based on the concept of absolute zero. Absolute zero is the lowest possible temperature at which the motion of particles becomes minimum.

The Kelvin scale starts from absolute zero (0 K), which is equal to −273°C. Unlike Celsius scale, Kelvin does not have negative values because it begins from this lowest limit.

Key Points:

• SI unit: Kelvin (K)
• Based on absolute zero
• 0 K = −273°C
• No negative values in Kelvin scale

Answer: Absolute zero

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🔹 Q14. Which surface reflects most heat?

Explanation:
Light-colored or white surfaces reflect most of the heat, while dark or black surfaces absorb more heat.

Key Points:

• White → reflects heat
• Black → absorbs heat
• Used in daily life (clothing)

Answer: White surface

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🔹 Q15. When ice melts, its temperature

Explanation:
During melting, the temperature remains constant because the heat supplied is used to change the state (solid to liquid), not to increase temperature.

Key Points:

• Temperature remains constant
• Heat used as latent heat
• State change occurs

Answer: Remains constant

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🔹 Q16. Which of the following is a good absorber and emitter of heat?

Explanation:
Black surfaces are the best absorbers and emitters of heat. They absorb maximum heat and also release it effectively.

Key Points:

• Black absorbs maximum heat
• Also best emitter
• Used in solar devices

Answer: Black surface

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🔹 Q17. The transfer of heat in solids mainly occurs by

Explanation:
In solids, heat is transferred through conduction, where energy passes from one particle to another without actual movement.

Key Points:

• No particle movement
• Energy transfer only
• Occurs in solids

Answer: Conduction

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🔹 Q18. What happens to the density of air when heated?

Explanation:
When air is heated, it expands, and its density decreases. This causes hot air to rise.

Key Points:

• Heating → expansion
• Density decreases
• Hot air rises

Answer: Decreases

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🔹 Q19. Which thermometer is used to measure human body temperature?

Explanation:
A clinical thermometer is used to measure human body temperature. It is designed for a specific range suitable for the human body.

Key Points:

• Range: 35°C to 42°C
• Used for body temperature
• Accurate for medical use

Answer: Clinical thermometer

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🔹 Q20. Heat transfer by electromagnetic waves is called

Explanation:
Heat transfer through electromagnetic waves without any medium is called radiation. Example: Heat from the Sun reaching Earth.

Key Points:

• No medium required
• Travels through vacuum
• Example: Sun’s heat

Answer: Radiation

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Real-Life Examples to Remember Concepts

• Hot tea cools down because heat flows from hot to cold surroundings
• We feel cool under a fan due to convection and evaporation of sweat
• Water in an earthen pot becomes cool because of evaporation
• Cooking utensils are made of metals due to good conduction of heat
• Utensil handles are made of plastic/wood because they are insulators
• Hot air rises (like in hot air balloons) because density decreases on heating
• Balloons expand when heated due to expansion of gases
• Black clothes feel hotter because they absorb more heat
• White clothes feel cooler because they reflect heat
• Sun’s heat reaches Earth through radiation (no medium required)
• Ice melts without temperature change due to latent heat concept
• Clinical thermometer is used to measure body temperature in daily medical use
• Water boils at 100°C (373 K), useful in cooking and boiling processes
• Air circulation in rooms happens due to convection currents
• Refrigerators work based on heat removal and temperature difference

Final Revision Tips (Quick Recall Before Exam)

• Temperature measures degree of hotness, heat is energy transfer
• Heat always flows from higher → lower temperature
• Gas expands most, then liquid, then solid
• Increase in temperature → increase in gas volume (Charles’ Law)
• Only 3 heat transfer modes: conduction, convection, radiation
• Conduction → solids, convection → fluids, radiation → no medium
• SI unit of temperature: Kelvin (K)
• Conversion: K = °C + 273
• Boiling point of water: 100°C = 373 K
• Absolute zero: 0 K = −273°C
• Black → absorbs heat, White → reflects heat
• During melting, temperature remains constant (latent heat)
• Heating air → density decreases → air rises
• Clinical thermometer range: 35°C to 42°C
• Radiation travels through vacuum (no medium needed)

🔗 Learn more:

For detailed explanation, refer to basic thermodynamics principles explained in NCERT Science textbooks, heat is a form of energy that flows from a hotter body to a colder body.