Know the main regions of the electromagnetic spectrum in order of frequency and in order of wavelength

3.3 Electromagnetic Spectrum

Order by Frequency (Highest → Lowest)

1. Gamma rays – the most energetic, like a superhero’s laser beam. \$f\$ = \$10^{19}\$–\$10^{20}\$ Hz
2. X‑rays – great for seeing inside objects, like a detective’s X‑ray vision. \$f\$ = \$10^{16}\$–\$10^{19}\$ Hz
3. Ultraviolet (UV) – the invisible part of sunlight that can burn your skin. \$f\$ = \$10^{15}\$–\$10^{16}\$ Hz
4. Visible light – the colours we can see, from red to violet. \$f\$ = \$4.3\times10^{14}\$–\$7.5\times10^{14}\$ Hz
5. Infra‑red (IR) – the heat you feel from a campfire. \$f\$ = \$10^{11}\$–\$10^{14}\$ Hz
6. Microwaves – used in ovens and Wi‑Fi, like a gentle kitchen heat. \$f\$ = \$10^{9}\$–\$10^{11}\$ Hz
7. Radio waves – the longest waves, used for music and TV. \$f\$ = \$10^{3}\$–\$10^{9}\$ Hz

Order by Wavelength (Shortest → Longest)

1. Gamma rays – \$\lambda\$ = \$10^{-12}\$–\$10^{-9}\$ m
2. X‑rays – \$\lambda\$ = \$10^{-9}\$–\$10^{-7}\$ m
3. Ultraviolet (UV) – \$\lambda\$ = \$10^{-7}\$–\$4\times10^{-7}\$ m
4. Visible light – \$\lambda\$ = \$4\times10^{-7}\$–\$7.5\times10^{-7}\$ m
5. Infra‑red (IR) – \$\lambda\$ = \$7.5\times10^{-7}\$–\$1\times10^{-3}\$ m
6. Microwaves – \$\lambda\$ = \$1\times10^{-3}\$–\$0.1\$ m
7. Radio waves – \$\lambda\$ = \$0.1\$–\$10^3\$ m