Infrared Waves in TV Remotes

Steps:

• Identify the function: TV remotes transmit signals wirelessly over short distances without wires.
• Recall electromagnetic spectrum: Components range from high-energy gamma rays to low-energy radio waves, with infrared in between visible light and microwaves.
• Match to application: Remote controls use light-like waves for line-of-sight communication, not penetrating waves.
• Confirm: Infrared is safe, invisible, and fits the low-power, directional needs of remotes.

Why B is correct:

• Infrared rays are electromagnetic waves with wavelengths of 700 nm to 1 mm, used in remotes to encode signals via modulation, as defined by their position in the spectrum for thermal and optical applications.

Why the others are wrong:

• A. Gamma rays: High-energy ionizing radiation used in medicine, too dangerous and penetrating for consumer devices.
• C. Radio waves: Longer wavelengths for broadcasting and communication, but require antennas and are not line-of-sight like remotes.
• D. Ultraviolet rays: Shorter than visible light, causes sunburns, and is used for sterilization, not signal transmission.

Final answer: B