Question 1: Define conduction and describe how it transfers heat through a material.

Answer: Conduction is the transfer of heat through a solid material by direct particle vibration, without the particles moving from their original positions.

Question 2: Explain the main difference between convection and radiation in the context of heat transfer.

Answer: Convection involves the movement of fluids (liquids or gases) carrying heat, whereas radiation transfers heat through electromagnetic waves without needing a medium.

Question 3: What type of heat transfer occurs when the Sun's energy reaches the Earth?

Answer: Radiation

Question 1: Calculate the amount of heat transferred (in joules) when 500 grams of aluminium (specific heat capacity = 900 J/kg°C) is heated by 20°C. Use the formula: Q = mcΔT.

Answer: Q = 900 × 0.5 × 20 = 9000 Joules

Question 2: A hot object radiates energy at a rate of 150 watts. How much energy (in joules) is radiated over 10 minutes? (Use Energy = Power × Time).

Answer: Energy = 150 × 600 = 90000 Joules

Question 1: Describe a simple experiment to demonstrate conduction using metals and explain the safety precautions you would take.

Answer: Use metal rods of different materials and heat one end while observing temperature changes at the other end with a thermometer. Wear heat-resistant gloves and safety goggles to prevent burns and eye injury.

Question 2: Identify the independent and dependent variables in an experiment measuring the rate of heat transfer by convection in a liquid.

Answer: Independent variable: Temperature difference or fluid properties; Dependent variable: Rate of heat transfer (temperature change over time).

Question 1: A metal plate is heated uniformly to 150°C. When exposed to infrared radiation, the heat energy measured over 5 minutes is 4500 Joules. Assuming all the energy transfer is due to radiation, what is the average power radiated in watts?

Answer: Power = 4500 J / 300 s = 15 Watts

Question 2: Interpret the data: What does the measured energy transfer suggest about the efficiency of infrared radiation in transferring heat from the metal plate?

Answer: The data suggests that infrared radiation can transfer significant amounts of heat efficiently over a short period, indicating it is a highly effective mode of heat transfer in this context.

Question 1: Explain how understanding conduction is important in designing heat sinks for electronic devices.

Answer: Understanding conduction helps in selecting materials with high thermal conductivity, like aluminium or copper, to efficiently transfer heat away from electronic components, preventing overheating.

Question 2: Describe a modern technological application that utilises radiation for heat transfer and briefly explain how it works.

Answer: Solar panels use radiation from the Sun to generate electricity. They absorb solar radiation through photovoltaic cells, converting light energy into electrical energy for practical use.