Physics - 0625 CIE

Radioactivity

Gbogbo ọrọ náà

Radioactivity is happening all around you right now: faint radiation from rocks, the air, your food and even outer space passes through you every second. Unstable nuclei throw out radiation at random, and learning to identify and measure it is the heart of nuclear physics.

In this lesson you will learn what background radiation is and where it comes from, how radiation is detected and counted, and the nature, ionising effect and penetrating power of alpha, beta and gamma radiation. You will also see how they behave in electric and magnetic fields and how to correct a count rate for background.

Ebumnobi

Know what is meant by background radiation
Know the sources that make a significant contribution to background radiation including: (a) radon gas (in the air) (b) rocks and buildings (c) food and drink (d) cosmic rays
Know that ionising nuclear radiation can be measured using a detector connected to a counter
Use count rate measured in counts / s or counts / minute
Describe the emission of radiation from a nucleus as spontaneous and random in direction
Identify alpha (α), beta (β) and gamma (γ) emissions from the nucleus by recalling: (a) their nature (b) their relative ionising effects (c) their relative penetrating abilities (β+ are not included, β-particles will be taken to refer to β-)
[Supplement] Use measurements of background radiation to determine a corrected count rate
[Supplement] Describe the deflection of α-particles, β-particles and γ-radiation in electric fields and magnetic fields
[Supplement] Explain their relative ionising effects with reference to: (a) kinetic energy (b) electric charge

Akọmọ Ojú-ẹkọ

Nuclear radiation is used in medicine, industry and dating, and it must be handled safely. Knowing which type penetrates what, and how strongly each ionises, lets you choose the right source for a job and the right shielding. Background correction is a small but frequently tested skill.

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Ayẹwo Ẹkọ

Ekele diri gi maka imecha ihe karịrị na Radioactivity. Ugbu a na ị na-enyochakwa isi echiche na echiche ndị dị mkpa, ọ bụ oge iji nwalee ihe ị ma. Ngwa a na-enye ụdị ajụjụ ọmụmụ dị iche iche emebere iji kwado nghọta gị wee nyere gị aka ịmata otú ị ghọtara ihe ndị a kụziri.

Ị ga-ahụ ngwakọta nke ụdị ajụjụ dị iche iche, gụnyere ajụjụ chọrọ ịhọrọ otu n’ime ọtụtụ azịza, ajụjụ chọrọ mkpirisi azịza, na ajụjụ ede ede. A na-arụpụta ajụjụ ọ bụla nke ọma iji nwalee akụkụ dị iche iche nke ihe ọmụma gị na nkà nke ịtụgharị uche.

Jiri akụkụ a nke nyocha ka ohere iji kụziere ihe ị matara banyere isiokwu ahụ ma chọpụta ebe ọ bụla ị nwere ike ịchọ ọmụmụ ihe ọzọ. Ekwela ka nsogbu ọ bụla ị na-eche ihu mee ka ị daa mba; kama, lee ha anya dị ka ohere maka ịzụlite onwe gị na imeziwanye.

Which is a source of background radiation? A. radon gas B. a torch battery C. a magnet D. sound waves Answer: A
Alpha radiation is best described as: A. an electron B. a helium nucleus C. an electromagnetic wave D. a proton Answer: B
Which radiation is stopped by a few millimetres of aluminium? A. alpha B. beta C. gamma D. none of them Answer: B
Which radiation is NOT deflected by a magnetic field? A. alpha B. beta C. gamma D. all are deflected equally Answer: C
A counter reads 90 counts/s near a source; background is 10 counts/s. The corrected count rate is: A. 100 counts/s B. 80 counts/s C. 9 counts/s D. 10 counts/s Answer: B