Why Correct: RADAR is an acronym for Radio Detection and Ranging, a system using radio waves to detect objects and determine their distance, speed, and direction.
Distractor Analysis: Ready Advanced Appliance for Ranging is a fabricated expansion with no technical basis. Range Detection Appliance Ranging incorrectly substitutes "Range" for "Radio" and creates a redundant phrase. Ready Advanced Airplane Ranging incorrectly associates RADAR solely with aircraft, though it applies to ships, weather, and ground targets too.
Takeaway: SONAR stands for Sound Navigation and Ranging, using sound waves underwater, while LIDAR uses Light Detection and Ranging with lasers.

Why Correct: RADAR (Radio Detection And Ranging) uses radio waves to detect, range, and determine the position of objects like aircraft, ships, and weather formations by analyzing reflected signals.
Distractor Analysis: Locating submerged submarines uses SONAR (Sound Navigation And Ranging), which employs sound waves. Receiving signals in a radio receiver describes the function of a radio receiver, not RADAR. Locating geostationary satellites typically uses ground-based tracking systems and telemetry, not RADAR's primary detection role.
Takeaway: SONAR uses sound waves for underwater detection, while RADAR uses radio waves for above-surface detection.

Why Correct: Microwaves occupy the 300 MHz to 300 GHz frequency range and are used for telecommunication, including satellite communication, mobile phones, and radar.
Distractor Analysis: Infra-red rays have frequencies below microwaves and are used for thermal imaging and remote controls. Ultra violet rays have higher frequencies than visible light and cause sunburn and vitamin D synthesis. X-rays have even higher frequencies and are used for medical imaging and material analysis.
Takeaway: The electromagnetic spectrum order from low to high frequency is: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays.

Why Correct: Kinetic energy in SHM is maximum at mean position and zero at extreme positions, occurring twice per complete oscillation.
Distractor Analysis: is never zero contradicts the zero velocity at extremes. is zero in the mean position reverses the actual maximum kinetic energy at equilibrium. is always constant ignores the energy conversion between kinetic and potential forms.
Takeaway: Potential energy in SHM is maximum at extremes and zero at mean position, exactly opposite to kinetic energy behavior.