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Uses and dangers of EM waves
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Each part of the electromagnetic spectrum has practical uses, and the high-energy parts carry risks.
Uses
Dangers
Microwaves: internal heating of body tissue.
Infrared: skin burns.
Ultraviolet: damage to surface cells, sunburn, skin cancer, blindness.
X-rays and gamma rays: ionising; can mutate DNA and cause cancer.
Infrared: skin burns.
Ultraviolet: damage to surface cells, sunburn, skin cancer, blindness.
X-rays and gamma rays: ionising; can mutate DNA and cause cancer.
Absorbing and emitting (Higher)
Changes in atoms and nuclei can generate or absorb EM radiation. Gamma rays come from changes in the nucleus.
Why are X-rays useful for imaging broken bones?
- X-rays pass through soft tissue.
- They are absorbed by dense bone.
- So bones show up as shadows.
Answer: Bone absorbs X-rays but soft tissue does not.
Radio for broadcasting, microwaves for cooking and satellites, infrared for heating and thermal imaging, UV for sterilising and security, X-rays and gamma for medicine. Higher-frequency waves are more dangerous.
The interactive lesson includes the diagrams for this topic.
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