A student researches three common technologies and records the characteristic electromagnetic wavelength or frequency for each, shown in the table below.
Device
Reported value
Cell-phone antenna
900MHz
Household microwave oven
2.45GHz
Red laser pointer
630nm
Assume 3.00×108m/s for the speed of light in vacuum.
(a) For each device, classify the electromagnetic region (e.g., infrared, ultraviolet) associated with the reported value. Show your reasoning, including any necessary unit conversions.
(b) Rank the three devices in order of increasing wavelength. Explain how the numerical values in the table support your ranking.
(c) Describe one practical reason—based on physical interaction with matter—why the specific wavelength or frequency used by each device is advantageous for its intended application.