Question 1: Define conduction, convection, and radiation in your own words.

Answer: Conduction is heat transfer through direct contact between particles, convection involves the movement of fluid due to temperature differences, and radiation is the transfer of heat through electromagnetic waves without needing a medium.

Question 2: Explain why metals are good conductors of heat.

Answer: Metals are good conductors because they have free electrons that transfer energy rapidly through the metal's structure.

Question 3: Describe a real-world example where convection is the primary method of heat transfer.

Answer: Boiling water in a kettle, where hot water rises and cooler water sinks, creating a convection current.

Question 1: A metal rod of mass 2 kg and specific heat capacity 385 J/kg°C is heated, causing its temperature to increase by 50°C. Calculate the amount of heat energy transferred to the rod. (Q = mcΔT)

Answer: Q = 385 × 2 × 50 = 38500 Joules

Question 2: If a lamp radiates heat energy at a rate of 100 watts for 30 minutes, how much energy is transferred? (1 watt = 1 joule/second)

Answer: Energy = Power × Time = 100 J/s × 1800 s = 180,000 Joules

Question 1: Describe an experiment to demonstrate conduction using different metals. Include variables to control and safety precautions.

Answer: Place different metal rods (e.g., copper, aluminium, iron) of equal length and cross-sectional area in contact with a hot source. Measure the temperature change at the far end over time. Control variables include the initial temperature and environment. Safety precautions involve handling hot equipment with tongs and wearing heat-resistant gloves.

Question 2: Identify three variables that could affect the rate of heat transfer in a convection experiment involving a fluid.

Answer: Temperature difference, fluid speed, and fluid viscosity.

Question 1: In a room, a radiator heats air which then circulates, warming the room. The temperature near the radiator is 70°C, while the far wall remains at 20°C. Explain which method of heat transfer is dominant and why.

Answer: Convection is dominant because the radiator heats the air, causing it to circulate and transfer heat throughout the room.

Question 2: A black surface exposed to sunlight heats up faster than a white surface. Explain the reason based on radiation principles.

Answer: Black surfaces absorb more electromagnetic radiation than white surfaces, so they heat up faster through radiation.

Question 1: Explain how double-glazed windows reduce heat loss through conduction and radiation.

Answer: Double-glazed windows have an air gap that reduces heat transfer by conduction and radiation. The glass also has a reflective coating that reflects infrared radiation back into the room.

Question 2: Identify a technological application that uses radiation for heat transfer and describe its function.

Answer: Solar panels use radiation from the Sun to transfer energy into electrical energy through photovoltaic cells.