USES OF EM WAVES

How are Radio Waves produced?

By oscillations (alternating currents) in electrical circuits.

How are Radio Waves detected?

When absorbed, they create an alternating current with the same frequency as the radio wave.

Radio Waves: Main uses

Television, radio transmissions, and satellite communications.

Radio Waves and Diffraction

Longer wavelengths allow radio waves to diffract (spread) around hills and the curvature of the Earth.

Radio Waves: Precautions/Hazards

Generally safe; at very high intensities, they can cause internal heating of body tissue.

Where do Gamma Rays originate from?

Changes in the nucleus of an atom (usually following radioactive decay).

Gamma Rays: Main uses

Sterilising medical equipment/food and targeted cancer treatment (radiotherapy).

Gamma Rays: Precautions/Hazards

Highly ionising and penetrative; can cause gene mutations or kill cells.

How are Visible Light, UV, and X-rays produced?

By changes in electron energy levels (electrons moving between shells).

Microwaves: Main uses

Satellite communications and cooking food (heating water molecules).

Microwaves: Precautions/Hazards

Can cause internal heating of body cells; prevented by metal shielding in ovens.

Infrared (IR): Main uses

Electrical heaters, infrared cameras (night vision), and cooking food.

Infrared (IR): Precautions/Hazards

Can cause skin burns if the skin is exposed to intense radiation.

Visible Light: Main uses

Vision, photography, and fibre optic communications.

Visible Light: Precautions/Hazards

Intense light (e.g., lasers) can cause permanent retinal damage to the eye.

Ultraviolet (UV): Main uses

Energy-efficient lamps, sun tanning, and bank note security.

Ultraviolet (UV): Precautions/Hazards

Can cause premature skin ageing, sunburn, and increased risk of skin cancer.

X-Rays: Main uses

Medical imaging (viewing bones) and airport security scanners.

X-Rays: Precautions/Hazards

Ionising radiation; can cause gene mutations and increase cancer risk.

What makes a wave 'Ionising'?

Having enough energy to knock electrons off atoms, which can damage DNA.

Which waves are ionising?

Ultraviolet, X-rays, and Gamma rays.

Relationship between frequency and danger

As the frequency of the wave increases, the energy and potential danger increase.

How do radiographers reduce X-ray risk?

Standing behind lead screens or wearing lead-lined aprons.

Why are Microwaves used for satellites?

They can pass through the Earth's atmosphere without being reflected or excessively diffracted.

Visible Light: Order of frequency

Red has the lowest frequency; Violet has the highest frequency.