Question 1: Explain in your own words why radio waves are used for broadcasting radio and television signals.

Answer: Radio waves have long wavelengths that can travel long distances and pass through the atmosphere, making them ideal for broadcasting signals over large areas.

Question 2: Which type of electromagnetic wave is primarily used in medical imaging techniques such as X-rays?

Answer: X-rays

Question 3: Fill in the blank: Ultraviolet light is used in __________ to sterilize equipment because it kills bacteria and viruses.

Answer: disinfection

Question 4: Describe how infrared waves are used in remote controls for televisions and other electronic devices.

Answer: Infrared waves are used in remote controls to send coded signals to the device by emitting infrared light that is detected by sensors, allowing control of the device wirelessly.

Question 5: Calculate the wavelength of a microwave with a frequency of 2.45 GHz. (Use the formula: wavelength = speed of light / frequency; speed of light = 3 x 10^8 m/s).

Answer: Wavelength = 3 x 10^8 m/s / 2.45 x 10^9 Hz = approximately 0.122 meters

Question 6: Identify one safety precaution that should be taken when working with ultraviolet light in laboratories.

Answer: Wearing protective goggles or UV safety glasses to prevent eye damage from UV exposure.

Question 7: Which part of the electromagnetic spectrum is most commonly used in satellite communications and why?

Answer: Microwaves are used because they can pass through the Earth's atmosphere and carry large amounts of data over long distances.

Question 8: Explain how gamma rays are used in cancer treatment.

Answer: Gamma rays are used in cancer treatment through a process called radiotherapy. They are directed precisely at cancerous tissues to destroy or damage cancer cells' DNA, preventing their growth and multiplication while minimizing damage to surrounding healthy tissue.

Question 9: Describe an experiment to demonstrate the use of infrared waves in thermal imaging.

Answer: Students can use a thermal camera or infrared sensor to detect heat emitted from various objects at different temperatures. By observing the infrared readings, they can compare how objects emit infrared radiation, demonstrating how thermal imaging detects temperature differences based on infrared emission.

Question 10: Identify a practical application of ultraviolet light outside of sterilization and explain its importance.

Answer: Ultraviolet light is used in forensic analysis to detect blood stains that are invisible to the naked eye, which is important for crime scene investigations.