- What is heat?
Heat is a form of energy that is transferred between objects due to a temperature difference. - Define temperature.
Temperature measures the average kinetic energy of particles in a substance. - What is conduction?
Conduction is the transfer of heat through a material without the movement of the material itself. - Name three good conductors of heat.
Copper, silver, and aluminum. - What is convection?
Convection is the transfer of heat by the movement of fluids (liquids or gases). - Give an example of heat transfer by radiation.
Heat from the Sun reaching the Earth. - What is a thermal conductor?
A material that allows heat to pass through it easily. - What is a thermal insulator?
A material that does not allow heat to pass through it easily. - What is the SI unit of heat?
Joule (J). - Define specific heat capacity.
The amount of heat required to raise the temperature of 1 kg of a substance by 1°C. - Why does metal feel cold to touch?
Because it conducts heat away from your hand quickly. - What is latent heat?
Heat absorbed or released during a phase change without a change in temperature. - What is the boiling point of water?
100°C (212°F). - What is the melting point of ice?
0°C (32°F). - Define thermal equilibrium.
When two objects are at the same temperature and no heat flows between them. - What is the role of a thermostat?
A thermostat controls the temperature of a system. - What is the difference between heat and temperature?
Heat is energy transfer due to temperature difference; temperature is a measure of energy. - What is thermal expansion?
The increase in the volume of a substance due to heating. - Why do metals expand on heating?
Because the kinetic energy of particles increases, causing them to move apart. - What is the principle of a thermos flask?
It minimizes heat transfer by conduction, convection, and radiation - Explain the process of conduction with an example.
Conduction is the transfer of heat through direct contact. For example, when a metal rod is heated at one end, heat travels to the other end through the vibrations of particles. - Describe the process of convection and its applications in daily life.
Convection involves the movement of warm fluids, creating a current. It is seen in boiling water, ocean currents, and heating systems. - Explain the greenhouse effect and its impact on global temperature.
The greenhouse effect is the trapping of heat by gases like CO₂, leading to a rise in Earth’s temperature. - What is radiation? Explain how it differs from conduction and convection.
Radiation is the transfer of heat in the form of electromagnetic waves. Unlike conduction and convection, it does not require a medium. - Why do we wear woolen clothes in winter?
Wool traps air, which acts as an insulator, keeping us warm. - Why are cooking utensils made of metal?
Because metals are good conductors of heat, allowing even cooking. - Why is the handle of a cooking pan made of wood or plastic?
Wood and plastic are insulators, preventing heat from reaching the hand. - Why does the sea breeze occur during the day?
Land heats up faster than water, causing warm air to rise and cool air from the sea to move in. - Why do black objects absorb more heat than white objects?
Black absorbs all wavelengths of light, converting them into heat.
Multiple Choice Questions
- Which of the following is a good conductor of heat?
(a) Rubber
(b) Wood
(c) Copper
(d) Plastic
Answer: (c) Copper - Which form of heat transfer does not require a medium?
(a) Conduction
(b) Convection
(c) Radiation
(d) Evaporation
Answer: (c) Radiation - The amount of heat required to raise the temperature of 1 kg of water by 1°C is called:
(a) Specific heat
(b) Latent heat
(c) Thermal capacity
(d) Thermal expansion
Answer: (a) Specific heat - What happens to the volume of most substances when they are heated?
(a) It increases
(b) It decreases
(c) It remains the same
(d) It first decreases and then increases
Answer: (a) It increases - Which of the following is a poor conductor of heat?
(a) Iron
(b) Copper
(c) Air
(d) Silver
Answer: (c) Air
Multiple Choice Questions
- Which unit is used to measure heat?
(a) Newton
(b) Joule
(c) Watt
(d) Pascal
Answer: (b) Joule - Which process is responsible for the warmth felt near a fireplace?
(a) Conduction
(b) Convection
(c) Radiation
(d) All of the above
Answer: (c) Radiation - Which of these is an example of convection?
(a) Heating a metal rod
(b) Boiling water
(c) Ironing clothes
(d) Sunlight reaching Earth
Answer: (b) Boiling water - The transfer of heat through direct contact is called:
(a) Radiation
(b) Convection
(c) Conduction
(d) Insulation
Answer: (c) Conduction - Which color is the best absorber of heat?
(a) White
(b) Red
(c) Black
(d) Yellow
Answer: (c) Black - What happens to water when it is cooled below 0°C?
(a) It evaporates
(b) It becomes steam
(c) It freezes into ice
(d) It condenses
Answer: (c) It freezes into ice - Which of the following is a poor conductor of heat?
(a) Copper
(b) Aluminum
(c) Air
(d) Silver
Answer: (c) Air - In which direction does heat flow naturally?
(a) From cold to hot
(b) From hot to cold
(c) In all directions equally
(d) It does not flow
Answer: (b) From hot to cold - Why do metal spoons become hot when placed in a hot soup?
(a) Convection
(b) Radiation
(c) Conduction
(d) Insulation
Answer: (c) Conduction - What is the latent heat of fusion?
(a) Heat required to raise temperature by 1°C
(b) Heat required to change liquid to gas
(c) Heat required to melt 1 kg of solid into liquid
(d) Heat lost by freezing
Answer: (c) Heat required to melt 1 kg of solid into liquid - Which type of heat transfer occurs when the sun heats the Earth?
(a) Conduction
(b) Convection
(c) Radiation
(d) Insulation
Answer: (c) Radiation - Why is mercury used in thermometers?
(a) It has a high specific heat
(b) It expands uniformly with temperature
(c) It has a high melting point
(d) It is a poor conductor of heat
Answer: (b) It expands uniformly with temperature - Which of the following materials is an insulator?
(a) Iron
(b) Wood
(c) Copper
(d) Aluminum
Answer: (b) Wood - What is the boiling point of water in Celsius?
(a) 0°C
(b) 50°C
(c) 100°C
(d) 212°C
Answer: (c) 100°C - When heat is removed from a gas, it becomes a:
(a) Liquid
(b) Solid
(c) Plasma
(d) Vapor
Answer: (a) Liquid - What is the device used to measure temperature?
(a) Barometer
(b) Thermometer
(c) Hygrometer
(d) Anemometer
Answer: (b) Thermometer - Which of the following best describes thermal equilibrium?
(a) Two objects have different temperatures
(b) No heat transfer between two objects
(c) Heat flows from one object to another
(d) One object gains heat, the other loses heat
Answer: (b) No heat transfer between two objects - Which state of matter has the highest energy?
(a) Solid
(b) Liquid
(c) Gas
(d) Plasma
Answer: (d) Plasma - What happens to the temperature of a substance during a phase change?
(a) It increases
(b) It decreases
(c) It remains constant
(d) It fluctuates
Answer: (c) It remains constant - What is the SI unit of temperature?
(a) Joule
(b) Kelvin
(c) Celsius
(d) Fahrenheit
Answer: (b) Kelvin - The process by which heat energy is transferred in a vacuum is:
(a) Convection
(b) Conduction
(c) Radiation
(d) Absorption
Answer: (c) Radiation - Why do we use double-walled glass in thermos flasks?
(a) To prevent heat loss by conduction
(b) To prevent heat loss by convection
(c) To prevent heat loss by radiation
(d) To prevent heat loss by all methods
Answer: (d) To prevent heat loss by all methods - Which of these substances expands the most when heated?
(a) Solids
(b) Liquids
(c) Gases
(d) All expand equally
Answer: (c) Gases - Why is water used as a coolant in car radiators?
(a) It has a low boiling point
(b) It has high specific heat capacity
(c) It is cheap
(d) It is non-toxic
Answer: (b) It has high specific heat capacity - What kind of heat transfer occurs in an electric heater?
(a) Conduction
(b) Convection
(c) Radiation
(d) Both conduction and radiation
Answer: (d) Both conduction and radiation - What is the purpose of insulation in houses?
(a) To increase heat flow
(b) To decrease heat flow
(c) To change the color of the house
(d) To create space
Answer: (b) To decrease heat flow - Which material will cool down faster, aluminum or wood?
(a) Aluminum
(b) Wood
(c) Both at the same rate
(d) None of these
Answer: (a) Aluminum - Which of the following is true about convection?
(a) It only occurs in solids
(b) It occurs in both solids and gases
(c) It only occurs in liquids and gases
(d) It cannot occur in water
Answer: (c) It only occurs in liquids and gases - Which type of heat transfer is used in microwave ovens?
(a) Conduction
(b) Convection
(c) Radiation
(d) Convection and radiation
Answer: (c) Radiation - The heat required to change a substance from liquid to gas is called:
(a) Latent heat of fusion
(b) Latent heat of vaporization
(c) Specific heat capacity
(d) Thermal expansion
Answer: (b) Latent heat of vaporization - Which is the best material for a cooking pot?
(a) Wood
(b) Iron
(c) Plastic
(d) Rubber
Answer: (b) Iron - Why is the Earth’s atmosphere important for maintaining temperature?
(a) It allows all heat to escape into space
(b) It traps heat like a greenhouse
(c) It reflects all heat back into space
(d) It prevents radiation
Answer: (b) It traps heat like a greenhouse - What property of metals makes them good conductors?
(a) High density
(b) Free electrons
(c) High melting point
(d) Low density
Answer: (b) Free electrons - Which process helps to keep the temperature of a swimming pool uniform?
(a) Conduction
(b) Convection
(c) Radiation
(d) Insulation
Answer: (b) Convection - Which device measures the quantity of heat?
(a) Thermometer
(b) Calorimeter
(c) Barometer
(d) Hygrometer
Answer: (b) Calorimeter - How does double glazing on windows help in keeping houses warm?
(a) Prevents conduction and convection
(b) Allows heat to escape
(c) Absorbs moisture
(d) Reflects heat
Answer: (a) Prevents conduction and convection - Why do dark colors feel warmer in sunlight?
(a) They reflect more heat
(b) They absorb more heat
(c) They conduct heat better
(d) They block the sun
Answer: (b) They absorb more heat - Why does ice melt faster on metal than on wood?
(a) Wood is colder
(b) Metal conducts heat better
(c) Wood conducts heat better
(d) Metal has less density
Answer: (b) Metal conducts heat better - Which material is used in vacuum flasks to reduce heat loss by radiation?
(a) Aluminum
(b) Glass
(c) Silver coating
(d) Rubber
Answer: (c) Silver coating - Which phenomenon makes warm air rise and cool air sink?
(a) Conduction
(b) Radiation
(c) Convection
(d) Reflection
Answer: (c) Convection - What is the principle behind solar panels?
(a) Absorption of light
(b) Reflection of heat
(c) Convection of heat
(d) Radiation of cold
Answer: (a) Absorption of light - What happens to the particles of a solid when it is heated?
(a) They stop moving
(b) They move closer together
(c) They vibrate faster and spread apart
(d) They become liquid
Answer: (c) They vibrate faster and spread apart - Why do metal roofs make noise when they expand or contract?
(a) Heat is absorbed
(b) Change in density
(c) Thermal expansion
(d) Evaporation of water
Answer: (c) Thermal expansion - Why does hot air balloon rise up in the air?
(a) Radiation
(b) Conduction
(c) Convection currents
(d) Gravity
Answer: (c) Convection currents - Which material is best suited for making handles of cooking utensils?
(a) Iron
(b) Plastic
(c) Copper
(d) Steel
Answer: (b) Plastic