Question 1: Define conduction in terms of energy transfer at the molecular level.

Answer: Conduction is the transfer of heat energy through a solid material by direct contact of particles, where energy is passed from molecule to molecule without the overall movement of the material.

Question 2: Describe how convection differs from conduction in transferring heat.

Answer: Convection involves the movement of fluid (liquid or gas) caused by temperature differences, leading to transfer of heat through bulk movement, whereas conduction occurs through direct molecular contact in solids without bulk movement.

Question 3: What is radiation, and how does it transfer heat without a medium?

Answer: Radiation is the transfer of heat through electromagnetic waves, such as infrared radiation, which can travel through vacuum or empty space without needing a medium.

Question 1: A metal spoon with a surface area of 0.02 m² absorbs 1000 J of heat energy in 50 seconds. Calculate the rate of heat transfer in watts.

Answer: 20 W

Question 2: A radiator emits infrared radiation with an intensity of 500 W/m². If the radiator's surface area is 1.5 m², what is the total power emitted?

Answer: 750 W

Question 1: Describe a simple experiment to demonstrate heat transfer by conduction using metal rods. Include the key variables involved and safety precautions.

Answer: One experiment involves heating one end of a metal rod (e.g., copper). The key variables are the material of the rod, temperature at the heated end, and duration. Safety precautions include wearing gloves to handle hot objects and using tongs or heat-resistant tools to avoid burns. Observations of temperature change along the rod demonstrate conduction.

Question 2: Identify the independent and dependent variables in an experiment measuring the rate of convection in water when heated.

Answer: Independent variable: Temperature of the water or heating power; Dependent variable: Rate of convection or speed of fluid movement.

Question 1: A home insulation material reduces heat loss by radiation. The surface temperature of the inner wall is 20°C, and the outer surface is 0°C. Explain how radiation contributes to heat loss and how insulation minimizes this effect.

Answer: Radiation contributes to heat loss by emitting infrared waves from the warm interior surface to the cooler exterior environment. Insulation materials, such as foam or fiberglass, reduce radiation heat transfer by reflecting or absorbing infrared rays, thus minimizing energy loss and maintaining indoor temperature.

Question 2: In an industrial process, a furnace heats metal parts via conduction and radiation. Explain which method is more efficient for heating the interior of the metal and why.

Answer: Radiation is more efficient for heating the interior of the metal because infrared radiation can penetrate surface layers and transfer heat more rapidly into the bulk of the material, especially at high temperatures.