S4.10.8 For the adult
Waves in communication and health
Amina calls her cousin across the sea, and her voice arrives in a fraction of a second. What carries it?
What this chapter teaches
A message is carried by changing a wave. Digital signals use pulses of 1 and 0, which can be cleaned on a long journey. Calls go by radio and microwaves, and by light in optical fibres. Ultraviolet, X-rays and gamma rays have packets with enough energy to damage DNA. Radio waves cannot ionise, but strong beams can heat.
Three questions to ask
There is no one right wording. Listen for the idea.
- How does a digital signal carry a message, and why is it good over a long distance?
- Why can X-rays harm living cells when radio waves cannot?
- What can you do to protect yourself from ultraviolet from the Sun?
After the chapter, the learner can
- Explain how radio, microwaves and light carry phone and internet signals
- Explain why ultraviolet, X-rays and gamma rays can harm living cells
What they copy into their notebook
A message changes a carrier wave. Digital: pulses of 1 and 0. Calls: radio and microwaves, light in fibres. UV, X-rays and gamma rays ionise and can damage DNA. Dose matters.