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There are three types of radiation: alpha, beta and gamma. An alpha particle is a helium nucleus and is made up of two protons, two neutrons and no electrons. A beta particle is an electron which comes from the nucleus of an atom. Gamma radiation is a high energy electromagnetic wave with really short wavelength and high frequency. Gamma rays are released when an atom is in a high energy state after emitting an alpha or beta particle to return to a stable state.

Nuclear equations describe what happens when a nucleus changes into another element by alpha or beta decay. In alpha decay, 2 protons and 2 neutrons are released from the nucleus to release an alpha particle, thus the atomic number decreases by 2 and the mass number decreases by 4. In beta decay, a neutron changes into a proton and releases an electron, thus the mass number stays the same and the atomic number increases by 1.

Background radiation that exists around us at all times. This can be from both naturally occuring or artificial sources. Some natural sources of background radiation are radon gas from radioactive emitting rocks and soil in the ground, cosmic rays that reach the Earth from space and living things, as plants absorb radioactive materials from the soil they grow in and pass them up through the food chain. Some artificial sources of background radiation are medical procedures and nuclear power and weapons. When conducting experiments involving radiation, the background radiation must first be calculated and deducted from all results so as not to interfere with them.

A source of gamma radiation emits gamma rays equally in all directions. This means that for a distance r from the source, the gamma rays are spread over the surface of a sphere with radius r and surface area 4ฯrยฒ. The intensity of the source is defined as the energy per unit time per unit area and can be calculated using I = E/4ฯrยฒ, where E = energy of the gamma rays and r = radius of sphere. As the distance from the source increases, the intensity of the gamma rays decreases, since they will be spread over a greater area. According to the formula for intensity, gamma radiation follows an inverse square law, meaning that the intensity of the source is directly proportional to the inverse of the square of the distance from the source.

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What are the three types of radiation?

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State what a gamma ray is.

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Define ionising power.

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Which type of radiation has the greatest range in air?

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Given that the radiation emitted from a radioactive sample cannot go through paper, of what type is it?

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What happens to a nucleus undergoing beta decay?

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A potassium nucleus โดยฒโโK emits a beta particle. Write the nuclear equation for this beta decay.

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Find the missing values of the given nuclear equation.

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Label the missing slices of the given pie chart representing the sources of background radiation.

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State why medical staff must wear protective gear while carrying out X-rays.

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