Sports
We have all seen how Olympic winners bite their medals after winning.
The reason is to check if the medal is of real gold.
It all started over 100 years ago when Olympic historians were unsure used to bite gold coins.
According to them, a small tooth mark on a coin indicated that it was made of real gold, which is more malleable than counterfeit gold-plated lead coins.
But now, the winners do it to just honour the tradition.
If you apply light pressure to gold, it changes shape. So, when a gold medal is bitten by teeth, the winners will see the teeth mark on their medal.
If it is only gold plated, the gold foil will scratch off. If it is a different metal, no teeth mark is visible.