Electromagnetic spectrum frequencies from devices

Steps:

• Recall electromagnetic spectrum: radio waves lowest frequency, then microwaves, infrared, visible, ultraviolet highest among these options.
• Identify waves: mobile phone uses radio/microwaves; sunbed emits ultraviolet; TV controller uses infrared; toaster produces infrared thermal radiation.
• Compare frequencies: ultraviolet > infrared > radio/microwaves.
• Select device with ultraviolet emission as highest frequency.

Why B is correct:

• Sunbed emits ultraviolet waves (frequency ~7.5–30 × 10^14 Hz) for skin tanning, per EM spectrum classification.

Why the others are wrong:

• A: Mobile phone emits radio waves (~10^9 Hz) for communication, much lower frequency.
• C: Television controller emits infrared waves (~3 × 10^11–4 × 10^14 Hz) for remote signals, below ultraviolet.
• D: Toaster emits infrared thermal radiation (~10^12 Hz) for heating, below ultraviolet.

Final answer: B