WS17B What Is Radioactivity?

Nuclear decay is a ____ process by which an unstable atomic nucleus ____ energy by emission of electromagnetic radiation or particle(s).

• regular, loses

• regular, gains

• random, loses

• random, gains

Nuclear decay is also known as ___ ___ or ___.

Ionisation refers to the ability to eject ____ from ____ to form ____. Since electrons are ejected, there will always be ___ protons than electrons. ___ are formed and they carry a ____.

____ have the highest ionising effect.

____ have the highest penetrating ability.

• alpha (α) particles,

  gamma (γ) rays

• alpha (α) particles,

  beta (β) particles

• gamma (γ) rays,

  alpha (α) particles

• gamma (γ) rays,

  beta (β) particles

____ have the lowest ionising effect.

____ have the least penetrating ability.

• alpha (α) particles,

  gamma (γ) rays

• alpha (α) particles,

  beta (β) particles

• gamma (γ) rays,

  alpha (α) particles

• gamma (γ) rays,

  beta (β) particles

____ have both medium ionising effect and medium penetrating ability.

• alpha (α) particles

• beta (β) particles

• gamma (γ) rays

An alpha (α) particle consists of 2 ___ and 2 ____ tightly bound together and is the ____ particle.

A beta (β) particle consists of _____.

When alpha (α) and beta (β) particles are emitted, ____ (γ) rays are also usually emitted.

Ionising radiation is radiation with high ____ that can knock off ____ from atoms to form ___.

In the figure, ultraviolet radiation, x rays and gamma rays are ____ radiation, while electromagnetic waves with ____ frequencies are non-ionising radiation.

What is the nuclear radiation detected in an environment where no radioactive source has been deliberately introduced?

Ionising nuclear radiation can be measured using a ____-____ (GM counter). The SI unit for radioactivity is the ____ ( __ ).

When carrying out any measurements with radioactive sources, the _____ radiation should be first measured and then subtracted from the measurements to obtain the corrected count rate for the radioactive source.