Term
| What did the equipment look like? |
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Definition
A drum on a stand.
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Term
| What was the viewing screen coated in (and why)? |
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Definition
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Zinc suphide because it flouresces (gives out a flash of light) when an alpha particle hits it.
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Term
| What could be moved round? |
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Definition
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The telescopic eyepiece with the zinc sulphide screen coated onto it.
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Term
| Why was the inside of the drum-like chamber maintained as a vacuum? |
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Definition
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If air had been in the chamber the alpha particles would have been absorbed by it even before they hit the gold foil. Alpha particles have a very low penetrating power.
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Term
| Why was gold chosen as the target? |
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Definition
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Gold leaf is a very thin gold foil. It is only a couple of atoms thick. Therefore it was possible to investigate how atoms affected 'missiles' fired at them by using such a foil. Not all metals can be made into such a fine foil.
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Term
| Why was gold chosen as the target? |
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Definition
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Gold leaf is a very thin gold foil. It is only a couple of atoms thick. Therefore it was possible to investigate how atoms affected 'missiles' fired at them by using such a foil. Not all metals can be made into such a fine foil.
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Term
| What is an alpha particle? |
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Definition
- it is a helium nucleus - made up of two protons and two neutrons. It therefore has a double positive charge and a mass of 4 atomic mass units (about 8000 times the mass of an electron).
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Term
| Where did Geiger and Marsden get their alpha particles from? |
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Definition
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A source of Radium held in a thin walled 1-mm diameter glass tube. Radium is a natural source of alpha particles.
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Term
| How did they measure the angle of deflection of the alpha particles? |
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Definition
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The telescope was mounted on a turntable that had a vernier scale marked onto it. They could read off the angle they had turned - count scintillations (flashes of light) for a set time and then turn to another angle and so on.
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Term
| Here is an animation of what happens... it is very good from http://regentsprep.org/Regents/
physics/phys05/catomodel/ruther.htm |
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Definition
Here is an animation of what happens... it is very good from http://regentsprep.org/Regents/
physics/phys05/catomodel/ruther.htm
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