Electromagnetic Waves

Characteristics of EM Waves

• Are transverse waves

• Made up of oscillating electric and magnetic fields

• Can travel without a medium and at a speed of 3×10⁸ m/s in a vacuum

• v=f x wavelength

• Frequency remains constant in different mediums

• Undergo reflections and refractions

• Transfer energy

• Ionising waves have higher frequencies and higher energies

• high temp bodies emit high frequency em waves

Uses for Radio Waves

• Communication

• Radio TV broadcast

• Radio astronomy

Uses of Microwaves

• Cooking

• Communications

Uses of Infrared

• Remote controls

• Data transfer

Uses for Visible Light

• Photography

• Telecommunication and Medicine

Uses for Ultraviolet

• Disinfection and sterilisation

• Anti-forgery features

Uses for X-rays

• Security scanning

• X-ray imaging

Uses for Gamma Rays

• Disinfection and sterilisation

• Radiotherapy

What are the harmful effects of over exposure to em waves

Heating - sunburn can cause skin aging and higher risk of skin cancer

Ionising radiation - come from outer space, natural radioactive materials or man-made

high energy em waves can penetrate our body (found in food and water)