Question 1: Define the term 'electromagnetic spectrum'.

Answer: The electromagnetic spectrum is the range of all types of electromagnetic radiation, organised by wavelength or frequency.

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

Answer: Radio waves are used to transmit signals over long distances in radio and television broadcasting, mobile phones, and satellite communications due to their ability to travel long distances with minimal energy loss.

Question 1: Which part of the electromagnetic spectrum is primarily used in microwave ovens, and why?

Answer: Microwaves are used because they can heat water and fat molecules efficiently through dielectric heating.

Question 2: Describe one medical application of X-ray radiation.

Answer: X-ray radiation is used in medical imaging to view bones and detect fractures or diseases inside the body.

Question 3: What is the main use of ultraviolet (UV) light in industry?

Answer: Ultraviolet light is used in sterilisation processes and in curing certain inks and adhesives.

Question 1: Calculate the wavelength of a radio wave with a frequency of 100 MHz. Use the speed of light as 3 x 10^8 m/s. (Wavelength = Speed / Frequency)

Answer: Wavelength = 3 x 10^8 m/s ÷ 1 x 10^8 Hz = 3 meters

Question 2: A UV lamp emits radiation with a wavelength of 250 nm. Calculate its frequency. (Speed of light = 3 x 10^8 m/s, 1 nm = 1 x 10^-9 m)

Answer: Frequency = 3 x 10^8 m/s ÷ 250 x 10^-9 m = 1.2 x 10^15 Hz

Question 1: Describe a basic experiment to demonstrate how infrared radiation is used in thermal imaging.

Answer: A practical experiment involves using an infrared camera or sensor to detect heat emitted from various objects at different temperatures. Students should observe that objects at higher temperatures emit more infrared radiation, which the camera visualises as different colours or intensities. Safety precautions include avoiding direct exposure to high-intensity infrared sources and ensuring proper handling of equipment.

Question 2: Identify three safety precautions that must be taken when working with gamma radiation in industrial or medical settings.

Answer: Wearing protective lead shielding, limiting exposure time, and using remote handling tools to avoid direct contact.

Question 1: A satellite uses microwave radiation to communicate with ground stations. Explain why microwaves are suitable for this purpose.

Answer: Microwaves can pass through the Earth's atmosphere with minimal absorption and can carry signals over long distances with relatively low energy loss.

Question 2: Explain how ultraviolet light is used in sterilising medical equipment.

Answer: Ultraviolet light destroys bacteria and viruses by damaging their DNA or RNA, making it effective for sterilising surfaces and equipment.

Question 3: In daily life, how do infrared sensors contribute to the functioning of remote controls?

Answer: Infrared sensors detect infrared radiation emitted by remote controls, allowing devices to receive signals and execute commands.