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

Answer: Absorption is the process by which a material takes in electromagnetic radiation, converting it into internal energy, thereby reducing the radiation's intensity.

Question 2: Explain how the absorption efficiency of a material varies with wavelength.

Answer: Absorption efficiency generally increases for wavelengths that correspond to the material's resonant frequencies, meaning materials absorb specific wavelengths more effectively depending on their properties.

Question 3: What is the significance of the absorption coefficient in measuring how well a material absorbs radiation?

Answer: The absorption coefficient quantifies the rate at which radiation is absorbed per unit distance within a material; higher values indicate greater absorption.

Question 4: Calculate the percentage of incident radiation absorbed by a material with an absorption efficiency of 75%.

Answer: Percentage absorbed = 75%

Question 5: Design a simple experiment to test the absorption of different materials. Mention at least two variables you would control.

Answer: An experiment could involve exposing different materials to a controlled source of electromagnetic radiation and measuring the transmitted or reflected radiation. Variables to control include the intensity and wavelength of the radiation source and the distance between the source and the materials.

Question 6: Data shows that a certain material absorbs 90% of infrared radiation at 1000 nm wavelength, but only 40% at 2000 nm. What does this suggest about the material's absorption spectrum?

Answer: It suggests that the material absorbs infrared radiation more effectively at shorter wavelengths around 1000 nm, indicating wavelength-dependent absorption properties.

Question 7: A black body at temperature T emits radiation with a peak wavelength λmax. If a material absorbs radiation most efficiently at this wavelength, how does this property affect its temperature regulation?

Answer: The material can effectively absorb and emit radiation at λmax, aiding in temperature regulation by balancing heat absorption and emission, which is crucial in thermal management.

Question 8: Multiple Choice: Which of the following factors most directly affect a material's absorption of electromagnetic radiation?

Answer: C) Wavelength of radiation

Question 9: Fill in the blank: The ability of a material to absorb specific wavelengths depends on its __________ and molecular structure.

Answer: composition

Question 10: Describe one real-world application where controlling absorption of radiation is important.

Answer: In solar panels, materials are designed to absorb maximum sunlight to convert it into electrical energy efficiently. Controlling absorption helps optimise energy capture.

Question 11: Explain why materials like aluminium foil are used as insulators in thermal applications.

Answer: Aluminium foil reflects a large portion of radiant heat, reducing absorption and thus helping to insulate by preventing heat transfer.

Question 12: What safety precautions should be considered when conducting experiments involving high-intensity radiation sources?

Answer: Use appropriate protective eyewear, avoid direct exposure to high-intensity radiation, and follow safety guidelines to prevent burns or eye damage.