Radioactivity – GCSE Physics

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What is Radioactivity?

  • An Atom is the basic unit of matter. Atom contains Electrons(negatively charged), Protons(positively charged) and Neutrons(neutral) in such a way that the protons and neutrons are present in nucleus and electrons revolve around them in orbitals.

  • The nucleus is present in center that contributes for mass of an Atom. The nucleus is positively charged due to the presence of Protons.

Illustration of an atom's structure, showing protons, neutrons, and electrons

  • When the nucleus of an Atom is Unstable then it releases some of its energy in the form of radiation from nucleus and becomes stable. This process of decay of an Atom is called Radioactivity.

Illustration of subatomic particles emitted from the nucleus during radioactive decay Here, subatomic particles are emitted from the nucleus

What are Background Radiations?

  • The Explosion of low level ionising radiations from the radioactive substances present naturally in our environment and from space.

Sources: The rocks containing small amount of Uranium produces Radioactive gas. The main source is Radon gas. This gas can enter into houses. Most of the high energy rays coming from sun are stopped in the upper atmosphere but some of them reach the surface of Earth and are known as Cosmic rays.

Illustration of radon gas entering a house through cracks in the foundation, walls, and water supply

Illustration of sources of background radiation, including cosmic rays, soil, and radon

  • Variation of Background radiation in different parts of the UK :
  • The amount of radioactive gas produced by rocks depends on the rock type.
  • Some foods naturally contain radioactive substances.
  • In hospitals, X-rays and Gamma-rays are used, which causes background radiation is caused.
  • High energy particles coming from the sun when could not be stopped by the atmosphere they reach at the surface of Earth causing background radiations and are called as Cosmic Rays.

How Radioactivity is measured? And Types of Radiation

Geiger-Müller tube and film badges for radiation detection and measurementGeiger-Müller tube and film badge for radiation dosimetry and monitoring

Two workers in protective suits handling radioactive materials

  • Types of Radiation:

    Warning sign for radiation danger

There are four kind of Radiations –

1) Alpha Radiation       

2) Beta Radiation

3) Gamma Radiation

4) Neutron Radiation

(1) Alpha Radiation (α) – When the nucleus shoots out an Alpha particle (two neutrons and two protons), we know that the helium atom also contains two protons and two neutrons in its nucleus. Thus, the radiation where Helium atom(without any electron) is emitted is called Alpha Radiation.

Illustration of alpha radiation particle emission

(2) Beta Radiation(β) –It generally occurs when a neutron in an atomic nucleus turns into proton and electron. The proton remains in the nucleus but the electron escapes the atom.

Illustration of beta radiation electron emission

3) Gamma Radiation (γ) – When an extremely high-energy photon(a small packet of light energy) escapes the nucleus which we call Gamma-ray. It is similar to emission of ordinary light from atom but the gamma ray can damage our surroundings. Gamma-rays involves high energy, The x-rays are similar to gamma-rays but are less energetic.

Illustration of gamma radiation high-energy photons

(4) Neutron Radiation (n) – Here a neutron escapes the nucleus of an atom. This is the most dangerous type of radiation.

Illustration of neutron radiation particle emission

# Brief Description about different types of Radiations –Warning sign for radiation danger

# How can we stop Radiations?

Different materials stopping alpha, beta, and gamma radiation

  • Alpha radiations consists of heavy and slowly moving particles with a lot of electrical charge, thus they can be easily stopped using a single sheet of paper.
  • Beta radiations consist of light and fast moving particles with electrical charge. This means that they can be stopped by thin plates of material.
  • Gamma radiations consists of fast moving particles with no electrical charge, they are harder to stop. We use dense material like Lead to stop Gamma-ray.
  • Neutron radiations consist heavy particles with no electrical charge. They can travel long distance. We need something that contains large amount of Hydrogen in it.

materials stopping alpha, beta, and gamma radiation

Applications of Radioactive Substances

Radioactive Substances are dangerous, but they also have many advantages, which is why we can apply them in our real life to resolve some problems, like –

  • Food naturally contains bacteria that eventually cause them to decompose. Some of them can result in food poisoning, but using gamma-rays we can irradiate them to make it safer to eat.

Benefits of radiation in medical and industrial applications

  • They can be used as Tracers. For example, following its path using the GM Tube to detect whether there is leakage from underground pipe. Higher level of radiations are observed at places of leakage.
  • Cancer diagnosis by tracers in the body.
  • Checking paper thickness.

Benefits of radiation in medical and industrial applications

Frequently Asked Questions

Solution:

  • Alpha decay, Beta decay, Gamma decay are primary types of radioactive decay

Solution:

  • Medical imaging, leakage detection and irradiating food to prevent food poisoning.

Solution:

  • No, the ionizing radiation is not always harmful but the higher doses are. Low doses are present naturally in our environment which we call Background radiations.

Solution:

  • The main resource is Radon gas from rocks and cosmic rays(sun rays that could not be stopped by Atmosphere).Also the rays used in Hospitals.

Solution:

  • Background radiation can enter in a house in multiple ways From the building material, soil and water, cosmic rays, rocks and through cracks etc.
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