Detection of radioactivity Flashcards – Cambridge IGCSE (9–1) Physics 0972 (Extended) (2026–2028)

What is background radiation?

Ionising radiation present in the environment even when no particular radioactive source is being investigated.

What factors affect the level of background radiation?

Location and circumstances.

What are four significant contributors to background radiation?

• Radon gas in the air
• Radioactive substances in rocks and building materials
• Radioactive substances in food and drink
• Cosmic rays from space

How do a detector and counter measure ionising nuclear radiation?

The detector responds to the radiation, and the counter records the resulting counts over a measured time interval.

How is count rate calculated?

$\text{count rate} = \frac{\text{number of counts}}{\text{time}}$

What are two units used to express count rate?

Counts per second and counts per minute.

What can cause a radiation detector to record background counts?

Background radiation.