Question 1: The electromagnetic spectrum includes all types of electromagnetic radiation, from radio waves to gamma rays. These waves differ in wavelength, frequency, and energy. Understanding these differences helps us recognise their uses and effects in daily life.

Answer: The electromagnetic spectrum covers all electromagnetic radiation, with waves differing in wavelength, frequency, and energy, and is important for various applications.

Question 1: Define wavelength and explain its significance in the electromagnetic spectrum.

Answer: Wavelength is the distance between successive crests or troughs of a wave; it determines the wave's position in the spectrum and its properties.

Question 2: Describe how the frequency of an electromagnetic wave relates to its energy.

Answer: Higher frequency waves have greater energy because energy is directly proportional to frequency (E = hf).

Question 1: Calculate the wavelength of a radio wave with a frequency of 100 MHz. (Use c = 3 x 10^8 m/s).

Answer: Wavelength = c / frequency = (3 x 10^8 m/s) / (100 x 10^6 Hz) = 3 meters.

Question 2: A gamma ray has a wavelength of 1 x 10^-12 meters. Calculate its frequency.

Answer: Frequency = c / wavelength = (3 x 10^8 m/s) / (1 x 10^-12 m) = 3 x 10^20 Hz.

Question 1: Describe a safe method to demonstrate the use of radio waves for communication in a classroom setting.

Answer: Use a remote-controlled device or a radio transmitter-receiver setup in a controlled environment, ensuring no interference with other electronic devices and following safety guidelines for handling electronic equipment.

Question 2: Identify two safety precautions when working with high-energy electromagnetic waves like gamma rays in a laboratory setting.

Answer: Use shielding materials such as lead to protect against radiation and limit exposure time to minimise health risks.

Question 1: A microwave oven operates at a frequency of 2.45 GHz. Describe how its wavelength compares to that of a visible light wave, and explain why microwaves are suitable for cooking.

Answer: Microwaves have a longer wavelength (~12 cm) compared to visible light (~400-700 nm). Their longer wavelength allows them to penetrate food and excite water molecules, generating heat efficiently for cooking.

Question 1: Explain how the energy of gamma rays compares to that of radio waves, and state one practical application of gamma rays in industry. (6 marks)

Answer: Gamma rays possess significantly higher energy than radio waves due to their much higher frequency. They are used in industry for sterilisation, medical imaging, and cancer treatment because of their ability to penetrate materials and destroy cells.

Question 1: Describe how electromagnetic waves are used in satellite communications and the importance of selecting the correct frequency band.

Answer: Electromagnetic waves carry signals between satellites and ground stations. Different frequency bands are chosen to avoid interference, ensure clear signals, and suit the transmission distance and data requirements.