Irradiation, Contamination and Dose · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Touched by rays or by dust

Science · Matter & Materials · ages 15-16
Name ______________________   Date ____________

  1. A dental X-ray irradiates a patient. What happens when the machine switches off?

    • The patient stays radioactive
    • The rays keep bouncing inside
    • The exposure ends at once

  2. A loaf passes through a beam that kills germs and comes out clean. What happened?

    • It was irradiated
    • It was contaminated
    • It became radioactive

  3. A tracer drunk for a scan travels to an organ and keeps emitting. What is this?

    • Plain irradiation from outside
    • Controlled contamination inside the body
    • A broken machine

  4. A worker gets a dose reading of 3 millisieverts. What should she do next?

    • Panic at once
    • Compare it with background levels and harm thresholds
    • Ignore it fully

  5. Why do iodine patients spit into the toilet and flush twice?

    • Because saliva and urine can carry radioactive material
    • To save water
    • Because iodine stains teeth

  6. Irradiated strawberries glow with radiation after treatment.

    Circle one:   True   False

  7. Two patients are scanned. One gets an X-ray, one gets a short-lived tracer. Why pick a short-lived tracer?

    • It costs less
    • It tastes nicer
    • It decays away quickly so the dose stays low

  8. Why does contamination usually carry the longer-lasting risk?

    • Rays travel faster than dust
    • The source stays and keeps emitting until cleared or decayed
    • Hospitals charge more for it
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Touched by rays or by dust W1-mt_WyxR7ZVEhi-s1

  1. The exposure ends at once · Irradiation is brief and over when the beam stops.
  2. It was irradiated · The beam passed through and left no material behind.
  3. Controlled contamination inside the body · The radioactive material now travels inside the patient.
  4. Compare it with background levels and harm thresholds · A dose number means little without its comparison.
  5. Because saliva and urine can carry radioactive material · Body fluids can carry the contamination to others.
  6. False · Irradiation leaves nothing radioactive behind.
  7. It decays away quickly so the dose stays low · Fast decay cuts the time the source spends emitting inside.
  8. The source stays and keeps emitting until cleared or decayed · Time with the source is what stretches the risk.
Worksheet · LightMySky