Question 1: Define the term 'absorption' in the context of black body radiation.

Answer: Absorption in black body radiation refers to the process by which a material takes in electromagnetic radiation, converting it into internal energy.

Question 2: Explain how the absorption of infrared radiation by atmospheric gases affects Earth's climate.

Answer: Absorption of infrared radiation by atmospheric gases traps heat in the atmosphere, contributing to the greenhouse effect and influencing Earth's climate.

Question 3: Describe the mechanism by which a black body absorbs all incident electromagnetic radiation across the spectrum.

Answer: A black body absorbs all incident electromagnetic radiation because it has an idealised surface with an emissivity of 1, meaning it does not reflect or transmit any radiation. The absorption occurs as the electromagnetic waves induce oscillations of charges within the material, converting the radiation energy into internal energy, which is then uniformly distributed throughout the body.

Question 4: Calculate the energy absorbed by a black body that absorbs 500 J of radiation over a period of 10 seconds. (Use the formula: Energy = Power × Time)

Answer: Energy = Power × Time = 500 J (since energy absorbed is given directly)

Question 5: List three practical applications where absorption properties of materials are utilised.

Answer: Thermal insulation, solar energy panels, infrared sensors.

Question 6: In an experiment to measure absorption, what variables must be controlled to ensure accurate results?

Answer: Variables to control include the intensity and wavelength of incident radiation, temperature of the black body, and the surface properties of the material.

Question 7: A material has an absorptivity of 0.8. If it is exposed to 1000 J of incident radiation, how much energy is absorbed?

Answer: Energy absorbed = absorptivity × incident energy = 0.8 × 1000 J = 800 J

Question 8: Analyse how the absorption properties of materials influence the design of thermal insulators.

Answer: Materials with high absorption and low emissivity are selected for thermal insulators because they effectively absorb and retain heat, reducing heat transfer. The surface texture and composition are engineered to maximize absorption of heat energy while minimising reflection and transmission, enhancing insulation efficiency.

Question 9: Identify the main safety precautions to consider when conducting experiments involving electromagnetic radiation absorption.

Answer: Use appropriate shielding to prevent exposure, avoid direct contact with high-energy sources, and follow safety guidelines for laser and infrared radiation use.

Question 10: Discuss the role of absorption in the development of photovoltaic cells (solar panels).

Answer: Absorption allows photovoltaic cells to convert sunlight into electrical energy. The materials used are designed to absorb specific wavelengths of sunlight efficiently, promoting electron excitation and current generation.