Which of the following electromagnetic waves is most energetic?

Step 1: Analyze the question We need to find which of the listed electromagnetic waves carries the most energy per photon.

Step 2: The concept The energy of an electromagnetic wave (photon) is given by:

E = hf = hc/λ

where h is Planck's constant, f is frequency, c is the speed of light, and λ is wavelength.

So energy is directly proportional to frequency and inversely proportional to wavelength. The higher the frequency (or shorter the wavelength), the more energetic the wave.

Step 3: The electromagnetic spectrum (lowest to highest energy)

Radio waves → Microwaves → Infrared → Visible light → Ultraviolet → X-rays → Gamma rays

• Radio waves: lowest frequency, longest wavelength, least energy
• Ultraviolet: higher frequency than visible light
• X-rays: higher frequency than UV
• Gamma rays: highest frequency, shortest wavelength, most energy

Step 4: Compare the options

| Option | Wave | Relative energy | |---|---|---| | A | Radio waves | Lowest | | D | Ultra-violet | Low-moderate | | B | X-ray | High | | C | Gamma rays | Highest |

Answer: C. Gamma rays

Exam tip: Remember the spectrum order with the phrase "Raging Martians Invaded Venus Using X-ray Guns" (Radio, Microwave, Infrared, Visible, UV, X-ray, Gamma). Energy and frequency increase from left to right, while wavelength decreases. Any "most energetic" question is then simply the one furthest right.