Electromagnetic spectrum — common mistakes

Always remember the order of the EM spectrum! A common mnemonic is 'Really Martians Invaded Venus Using X-ray Guns' (Radio, Microwave, Infrared, Visible, Ultraviolet, X-ray, Gamma). Also, be precise with the speed of light value: $3.00 x 10⁸ m s^{-1}$.

Electromagnetic waves are transverse, can travel through a vacuum, and always move at the speed of light in a vacuum. Sound waves are longitudinal, require a medium to travel, and are much slower.

Our eyes have evolved to detect only a narrow range of wavelengths (400-700 nm) within the vast EM spectrum. This range is likely due to the specific light energies most abundant and useful on Earth's surface for vision.

The energy of an EM wave is directly proportional to its frequency and inversely proportional to its wavelength, as described by the Planck-Einstein relation $E = hf$. So, gamma rays (highest frequency, shortest wavelength) carry the most energy, while radio waves (lowest frequency, longest wavelength) carry the least.