iGCSE Physics (0625) 3.3 Electromagnetic spectrum-Exam Style Questions- New Syllabus
▶️ Answer/Explanation
Detailed solution:
Mobile phones primarily use microwaves for communication because they can penetrate certain obstacles and require only short aerials for transmission.
Security scanners, particularly those used in airports for baggage or medical scanning, utilize $X-rays$ due to their high penetrative ability through solid objects.
Intruder alarms often rely on passive infrared sensors that detect the $infrared$ radiation (thermal energy) emitted by human bodies.
According to the syllabus, microwaves correspond to application $1$, $X-rays$ to application $2$, and infrared to application $3$.
Matching these specific requirements to the provided table, Row D is the only option that correctly identifies all three electromagnetic regions.
Therefore, the correct sequence of waves for the given list is microwaves, $X-rays$, and infrared.
▶️ Answer/Explanation
Detailed solution:
High-frequency electromagnetic waves carry enough energy to ionize atoms and damage biological cells. According to the syllabus, ultraviolet ($UV$) radiation causes damage to surface cells and eyes, potentially leading to skin cancer. $X$-rays and $\gamma$-rays (gamma rays) possess even higher frequencies and can cause deeper mutations or significant cell death. In contrast, visible light (such as green and red) and radio waves do not have sufficient energy per photon to cause this type of ionising cell damage. Therefore, both gamma rays and ultraviolet are correct answers.
▶️ Answer/Explanation
Detailed solution:
Remote controllers use pulses of electromagnetic radiation to communicate with electronic devices like televisions.
Infrared radiation is the standard choice for this application because it can carry data over short distances and does not pass through walls, preventing interference between rooms.
Other parts of the spectrum like $X-rays$ or $gamma~rays$ are high-energy ionizing radiations that would be hazardous to health.
Ultraviolet radiation is also unsuitable as it is primarily used for applications like sterilization or security marking.
According to the syllabus, infrared is specifically used for short-range communications such as remote controllers.
Therefore, the correct radiation type is infrared radiation, making Option B the correct answer.