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

Answer: Emission refers to the process by which a hot object releases electromagnetic radiation, particularly infrared and visible light, as it heats up.

Question 2: Explain why objects emit different colours when heated to various temperatures.

Answer: Objects emit different colours because the wavelength of the radiation they emit depends on their temperature; higher temperatures produce shorter wavelengths, shifting emission from red towards blue.

Question 3: What is meant by a 'black body' in physics?

Answer: A black body is an idealised object that absorbs all incident electromagnetic radiation and emits a characteristic spectrum of radiation depending on its temperature.

Question 4: Describe the mechanism by which a hot object emits electromagnetic radiation.

Answer: A hot object emits electromagnetic radiation as a result of the thermal vibrations of atoms and molecules. As they vibrate more vigorously at higher temperatures, energy is released in the form of photons, producing a spectrum of emitted radiation characteristic of the object's temperature.

Question 5: A black body at 6000 K emits visible light. What colour is this emission most likely to be?

Answer: Yellow

Question 6: Complete the sentence: As the temperature of a black body increases, the peak wavelength of its emitted radiation shifts __________.

Answer: to shorter wavelengths

Question 1: Calculate the wavelength at which a black body at 3000 K emits its peak radiation using Wien's Law. (Wien's constant, b = 2.898 x 10^-3 m·K).

Answer: Wavelength = 9.66 x 10^-7 m

Question 2: A star emits peak radiation at a wavelength of 500 nm. Using Wien's Law, estimate its surface temperature.

Answer: Temperature ≈ 5796 K

Question 1: Describe a simple experiment to observe the emission of radiation from a heated metal wire. Include the variables you would measure and safety precautions.

Answer: Heat a thin metal wire, such as nichrome, using a controlled power supply. Observe the colour change as the wire heats up. Measure the temperature with a thermometer or infrared sensor. Variables include voltage, current, and temperature. Safety precautions involve wearing eye protection, ensuring proper insulation, and avoiding contact with the hot wire to prevent burns.

Question 2: Identify two variables that could affect the amount of emission from a heated object in an experiment.

Answer: The temperature of the object and the material's properties (such as surface area and composition).

Question 1: A black body radiator operating at 800 K emits primarily in the infrared spectrum. Explain how this principle is utilised in remote controls and thermal imaging devices.

Answer: Devices like remote controls use infrared emitters to send signals because infrared radiation is emitted efficiently at 800 K. Thermal imaging cameras detect emitted infrared radiation from objects, allowing us to see heat patterns. This utilisation relies on understanding emission spectra at different temperatures.

Question 2: Describe how industries use emission principles to monitor and control temperature in manufacturing processes.

Answer: Industries use infrared sensors and pyrometers to measure emission spectra from materials, allowing non-contact temperature monitoring. Controlling emission helps ensure processes like metal forging, glass production, and chemical manufacturing operate within specified temperature ranges for quality and safety.