Electromagnetic Spectrum Properties and Risks

Flashcards covering the wavelength, frequency, uses, mechanisms, and risks of various bands in the electromagnetic spectrum.

Radio Waves — Wavelength

$1\,mm$ to over $100\,km$

Radio Waves — Frequency

$3\,kHz$ to $300\,GHz$

Radio Waves — Uses

TV, radio signals, and maritime communication.

Radio Waves — How they work

Transmitters vibrate electrons to emit waves; receivers capture them to match frequencies.

Radio Waves — Risks

Non-ionizing. No known significant health risks at everyday exposure levels.

Microwaves — Wavelength

$1\,mm$ to $1\,m$

Microwaves — Frequency

$300\,MHz$ to $300\,GHz$

Microwaves — Uses

Satellite communication, Wi-Fi networks, radar, and cooking food.

Microwaves — How they work

Pass cleanly through the atmosphere; spin water molecules in food to create heat.

Microwaves — Risks

Non-ionizing. Can cause internal heating of body tissue at exceptionally high intensities.

Infrared (IR) — Wavelength

$700\,nm$ to $1\,mm$

Infrared (IR) — Frequency

$300\,GHz$ to $430\,THz$

Infrared (IR) — Uses

TV remote controls, thermal imaging, and short-range data links.

Infrared (IR) — How they work

Warm objects emit IR; thermal sensors map the heat while remotes send light codes.

Infrared (IR) — Risks

Non-ionizing. Overexposure causes thermal burns to skin and can damage eyes (cataracts).

Visible Light — Wavelength

$400\,nm$ (violet) to $700\,nm$ (red)

Visible Light — Frequency

$430\,THz$ to $750\,THz$

Visible Light — Uses

Human vision, photography, and fibre-optic communications.

Visible Light — How they work

Bounces off objects into eyes; reflects inside glass strands via total internal reflection.

Visible Light — Risks

Non-ionizing. Generally safe, but intense concentrated light (lasers) can permanently damage retina cells.

Ultraviolet (UV) — Wavelength

$10\,nm$ to $400\,nm$

Ultraviolet (UV) — Frequency

$750\,THz$ to $30\,PHz$

Ultraviolet (UV) — Uses

Sterilising medical equipment, sunbeds, and security markings.

Ultraviolet (UV) — How they work

Snaps the DNA bonds of microbes; special inks absorb UV and glow as visible light.

Ultraviolet (UV) — Risks

Ionizing (borderline). Damages skin cells, leading to sunburn, premature aging, and skin cancer. Can cause cataracts.

X-rays — Wavelength

$0.01\,nm$ to $10\,nm$

X-rays — Frequency

$30\,PHz$ to $30\,EHz$

X-rays — Uses

Medical imaging of bones and airport luggage security scanners.

X-rays — How they work

Blast through soft tissue but are absorbed by dense bone, casting a shadow image.

X-rays — Risks

Highly Ionizing. Penetrates deeply. Breaks chemical bonds, damages DNA, causes gene mutations, and increases cancer risk.

Gamma Rays — Wavelength

Less than $0.01\,nm$

Gamma Rays — Frequency

Greater than $30\,EHz$

Gamma Rays — Uses

Radiotherapy to treat cancer and sterilising medical supplies.

Gamma Rays — How they work

High-energy beams are targeted straight at tumours to mutate and destroy cancer cells.

Gamma Rays — Risks

Extremely Ionizing. Highest penetration power. Destroys cells, alters DNA, causes radiation sickness, and heavily increases cancer risk.