Question 1: Define the electromagnetic spectrum and list its main regions in order of increasing wavelength.

Answer: The electromagnetic spectrum is the range of all types of electromagnetic radiation, ordered by wavelength from shortest to longest: gamma rays, X-rays, ultraviolet, visible light, infrared, microwaves, radio waves.

Question 2: Explain how radio waves are used in communication technologies.

Answer: Radio waves are used to carry signals over long distances in television, radio broadcasting, and mobile phone networks because they can travel through the atmosphere and penetrate buildings.

Question 1: Describe the main difference between ionising and non-ionising radiation within the EM spectrum.

Answer: Ionising radiation has enough energy to remove electrons from atoms, potentially causing damage, while non-ionising radiation does not have sufficient energy to ionise atoms.

Question 2: What is the mechanism by which gamma rays can kill cancer cells?

Answer: Gamma rays can kill cancer cells by damaging their DNA through ionisation, leading to cell death or preventing replication.

Question 1: Calculate the wavelength of a gamma ray with a frequency of 1 x 10^20 Hz. (Use the speed of light c = 3 x 10^8 m/s)

Answer: wavelength = speed of light / frequency = (3 x 10^8 m/s) / (1 x 10^20 Hz) = 3 x 10^-12 meters

Question 2: A radio wave has a wavelength of 2 meters. What is its frequency?

Answer: frequency = speed of light / wavelength = (3 x 10^8 m/s) / 2 m = 1.5 x 10^8 Hz

Question 1: Describe an experiment to detect ultraviolet radiation from sunlight. Include the variables involved and safety precautions.

Answer: An experiment can involve using a UV-sensitive paper that changes colour when exposed to UV radiation. Variables include the duration of exposure, distance from the sun, and the type of material covering the paper. Safety precautions include wearing UV-protective gloves and sunglasses to prevent skin and eye damage, and performing the experiment in a controlled outdoor environment to avoid overexposure.

Question 1: A mobile phone transmits signals at a frequency of 2.4 GHz. Explain how the properties of this wave allow it to be used for communication, and discuss any safety considerations associated with its use.

Answer: The 2.4 GHz frequency falls within the microwave region, allowing signals to penetrate buildings and cover long distances. Its wavelength enables efficient transmission with minimal loss. Safety considerations include limiting exposure to prevent heating of body tissues, although typical usage levels are considered safe by health authorities.

Question 1: Explain why gamma rays are used in cancer radiotherapy, and discuss any risks associated with their use. (6 marks)

Answer: Gamma rays are used in cancer radiotherapy because they can penetrate deep into tissues and damage the DNA of cancer cells, leading to cell death. Risks include damage to surrounding healthy tissue, potential radiation sickness, and increased risk of secondary cancers if not carefully controlled.