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Jean-Louis
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I have a copper coin with a hole in the centre. The hole is a circle. If the coin is heated, the metal will expand towards all directions in and out, so the radius of the circle will be decreased. Correct?
Incorrect. Do the exercise that cesiumfrog suggests. All linear dimensions will expand, including that of the hole.Jean-Louis said:I have a copper coin with a hole in the centre. The hole is a circle. If the coin is heated, the metal will expand towards all directions in and out, so the radius of the circle will be decreased. Correct?
If the radius decreased, what could you say about the interatomic spacing in the tangential direction, along this inner wall? Would it have increased or decreased? What would you expect heating to produce (an increase or a decrease in the interatomic spacing)?Jean-Louis said:I have a copper coin with a hole in the centre. The hole is a circle. If the coin is heated, the metal will expand towards all directions in and out, so the radius of the circle will be decreased. Correct?
Yes, heating a copper coin can change the radius of its centre hole. This is due to thermal expansion, which is the phenomenon of materials expanding when heated and contracting when cooled. Copper is known to have a high coefficient of thermal expansion, meaning it expands significantly when heated. This expansion can cause the centre hole of a copper coin to increase in size.
The exact amount of change in the radius of the centre hole would depend on several factors, including the initial size of the hole and the temperature at which the coin is heated. However, in general, the change in radius would be small and likely only measurable with precise equipment.
No, the change in the radius of the centre hole would not be permanent. Once the coin cools down, it would return to its original size and shape. This is because thermal expansion is a reversible process, meaning the material will return to its original state once the temperature changes.
Yes, there are other ways to change the radius of the centre hole in a copper coin, such as mechanical deformation or chemical etching. However, these methods would result in a permanent change in the radius and may also affect the overall shape and appearance of the coin.
Heating a copper coin may affect its value or authenticity, depending on the methods used and the purpose of the heating. If the heating is done for scientific purposes or as a means to change the physical properties of the coin, it may not affect its value or authenticity. However, if the heating is done in an attempt to alter the coin's appearance or deceive collectors, it would likely decrease its value and be considered fraudulent.