IGCSE 0625 / Section 5.2.5 / Core

Distance, time, shielding.

Ionising radiation does its damage quietly, cell by cell, with no warning you can feel. The defences are simple and powerful: stay back, keep it brief, and put something dense in the way.

The key idea

Ionising radiation damages living cells, so exposure must be kept as low as possible. The dose is reduced by keeping your distance, limiting the time of exposure, and shielding with dense materials such as lead. Sources are stored in lead-lined containers and handled with tongs.

Definition · learn the exact words

Ionising radiation is dangerous because it can damage or kill living cells and cause mutations. Exposure is reduced by increasing distance, reducing time, and using shielding.

keep your distance · limit the time · shield with lead

Sources are stored in lead-lined containers and handled with tongs, never bare hands.

Section 01

Lower the dose.

Adjust distance, time and shielding and see how each lowers the radiation dose.

Stage 1 · Learn

Check safety

Four quick checks. Each correct answer earns XP and lights this skill on your star map.

Quick check+10 XP

Ionising radiation is dangerous because it can...

Quick check+10 XP

A radioactive source in a laboratory should be handled with...

Quick check+10 XP

Which set of actions reduces a person’s radiation dose?

Quick check+10 XP

Radioactive sources are stored in...

Section 02

Three defences, and good handling.

Distance, time and shielding cut the dose; careful storage and handling keep it that way.

Examiner trap

The three ways to cut your radiation dose are distance, time and shielding: stay further away, spend less time near the source, and put dense material such as lead between you and it.

Stage 2 · Exam

Exam-style questions

Unlocks once the four checks above are done. Worth more XP, written in the style of Paper 2.

Finish the four checks above to unlock the exam questions
Exam style+20 XP

Which material is best for shielding against gamma radiation?

Exam style+20 XP

A worker wants to reduce the dose received while moving a source. The most effective single action is to...

Exam style+20 XP

Why are radioactive sources handled with long tongs rather than fingers?

Skill unlocked

Safety, mastered.

Radiation safety completes the radioactivity strand and Unit 5. Keep the chain going.

-Rank -Level -Score -Topics
Go deeper · practice
Six original Cambridge-style questions
The dangers of ionising radiation and reducing dose by distance, time and shielding, plus safe handling and storage. Attempt each, then reveal the worked solution.
Stage 3 · master the unit
Nuclear physics challenge
Mixed questions across the whole unit, each one worth XP. Start this only when you feel confident across every topic in the unit, not just safety.
Start the unit challenge →