Correct Answer - Option 3 : Gamma
Concept:
The energy of the three radiations is absorbed by the material through which the radiation passes. The amount of energy which is absorbed depends on the type of radiation and the type of the absorbing material.
The range of the alpha radiation in an absorbing material is less than that of beta or gamma. The alpha radiation transfers more energy to an absorber than beta or gamma radiation. Alpha radiation is absorbed by the thickness of the skin or by a few centimetres of air.
Beta radiation is more penetrating than alpha radiation. It can pass through the skin, but it is absorbed by a few centimetres of body tissue or a few millimetres of aluminium.
Gamma radiation is the most penetrating of the three radiations. It can easily penetrate body tissue. It requires several centimetres of lead or about 1 metre of concrete to absorb it.
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The table below shows the properties of each type of ionising radiation
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Radiation
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Range (cm)
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Ionising power
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Can pass through paper?
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Can pass through 5mm of aluminum
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Can pass through 5cm of lead?
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Electrical field deflection
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Alpha
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3-5
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Highly ionising
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No
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No
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No
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Deflected towards negative plate
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Beta
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about 15
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Ionising
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Yes
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No
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No
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Deflected towards positive plate
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Gamma
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much longer
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Weakly ionising
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Yes
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Yes
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No - although some will still get through
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None
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