Question 1: Define the term 'electromagnetic spectrum'.

Answer: The range of all types of electromagnetic radiation, arranged according to wavelength or frequency.

Question 2: Explain why radio waves are suitable for long-distance communication.

Answer: Because they have long wavelengths that can travel long distances without significant absorption or scattering.

Question 3: Multiple Choice: Which part of the EM spectrum is primarily used in medical X-ray imaging?

Answer: X-rays

Question 1: Calculate the energy of a photon of ultraviolet light with a wavelength of 300 nm. Use the formula: E = hc/λ, where h = 6.626 x 10⁻³⁴ Js, c = 3.00 x 10⁸ m/s. Provide your answer in joules (J).

Answer: 6.63 x 10⁻¹⁹ J

Question 2: A microwave oven operates at a frequency of 2.45 GHz. Calculate its wavelength. Use the formula: λ = c/f.

Answer: approximately 0.122 m

Question 1: Design a simple experiment to investigate how different materials absorb infrared radiation. Identify the independent and dependent variables and mention safety considerations.

Answer: Students could use infrared sensors to measure heat absorption on materials like aluminium foil, cloth, and plastic. The independent variable is the material type; the dependent variable is the temperature increase. Safety precautions include avoiding direct contact with hot materials and using protective gloves if necessary.

Question 1: A satellite uses radio waves at a frequency of 1 GHz to transmit signals to Earth. The data shows that the satellite's signal travels a distance of 3 x 10⁸ km in 0.5 seconds. Calculate the speed of the signal and comment on whether it matches the expected speed of electromagnetic waves.

Answer: Speed = distance / time = (3 x 10⁸ km) / 0.5 s = 6 x 10⁸ km/s (which equals 3 x 10⁸ m/s). This matches the speed of electromagnetic waves in a vacuum, confirming the data's consistency.

Question 2: Identify two industries or applications that rely on the use of ultraviolet light, and explain the scientific principle behind each.

Answer: UV light is used in sterilisation of medical equipment, as it can destroy bacteria and viruses. It is also used in forensic analysis to detect bodily fluids, as many substances fluoresce under UV light due to their chemical composition.

Question 1: Describe how infrared radiation is utilised in night-vision technology. Include the scientific principle involved and potential limitations.

Answer: Night-vision devices detect infrared radiation emitted by warm objects, converting it into visible images. The principle involves thermal radiation detection, allowing users to see in darkness. Limitations include reduced effectiveness in cold environments and the need for sensitive equipment.

Question 2: Multiple Choice: Which electromagnetic wave is primarily used in sterilising medical equipment due to its ability to destroy bacteria?

Answer: Gamma rays