Question 1: Explain in your own words what is meant by 'emission' in the context of black body radiation.

Answer: Emission refers to the process by which a black body emits electromagnetic radiation due to its temperature, primarily in the form of infrared, visible light, or ultraviolet depending on the temperature.

Question 1: What does a black body mean in terms of radiation absorption and emission?

Answer: A black body is an idealised object that absorbs all incident radiation and emits radiation characteristic of its temperature without reflection or transmission.

Question 2: Describe how the temperature of a black body affects its emission spectrum.

Answer: As the temperature increases, the black body emits more radiation at all wavelengths, and the peak of the emission spectrum shifts towards shorter wavelengths (higher frequencies).

Question 1: Calculate the power emitted per unit area by a black body at a temperature of 6000 K using the Stefan-Boltzmann Law: P/A = σT^4, where σ = 5.67 × 10^-8 W/m^2K^4.

Answer: 0.5 W/m^2

Question 2: A star has a surface temperature of 5500 K. What is the wavelength at which its emission peaks? Use Wien's Law: λ_max = b / T, where b = 2.898 × 10^-3 m·K.

Answer: 5.27 × 10^-7 m (or 527 nm)

Question 1: Describe a simple experimental setup to demonstrate black body emission and list two safety precautions to consider.

Answer: A typical setup involves heating a cavity with a small opening, such as a blackened metal box heated by an electric heater or a high-temperature filament. The emitted radiation can be analysed with a spectrometer. Safety precautions include ensuring proper insulation to prevent burns and avoiding direct exposure to intense infrared radiation.

Question 1: A black body at 3000 K emits a peak wavelength at approximately 966 nm. Explain what this indicates about its temperature and the type of radiation it predominantly emits.

Answer: The peak wavelength of 966 nm indicates the black body is relatively hot, emitting predominantly infrared radiation. The temperature aligns with the given 3000 K, consistent with the Wien's Law for peak emission wavelength.

Question 2: If a star's emission spectrum shifts towards shorter wavelengths over time, what does this suggest about the star's temperature? Provide a scientific explanation.

Answer: A shift towards shorter wavelengths suggests an increase in the star's surface temperature, as per Wien's Law. This means the star is getting hotter, emitting more energy at higher frequencies, causing the peak of its emission spectrum to move to the blue or ultraviolet region.

Question 1: Describe how understanding black body emission helps in designing thermal imaging cameras used in night vision technology.

Answer: Thermal imaging cameras detect infrared radiation emitted by objects due to their temperature. Understanding black body emission allows engineers to calibrate these devices accurately, enabling them to visualise temperature differences in darkness or through obstructions.

Question 2: Explain the significance of black body radiation in the development of solar panels and energy harvesting technologies.

Answer: Black body radiation principles underpin the design of solar panels by helping scientists understand how materials absorb and emit electromagnetic radiation across different wavelengths. This knowledge optimises the materials used in photovoltaic cells to maximise energy absorption from sunlight, improving the efficiency of solar energy harvesting.