A short chain is usually attached to the back of a petrol tanker and trailing behind it so that the
Answer Details
The purpose of a short chain attached to the back of a petrol tanker and trailing behind it is to ensure that any charges generated by friction in the tanker are conducted to the earth. This is done to prevent any static electricity buildup, which could potentially lead to dangerous sparks or even explosions when the petrol is being pumped or transferred. The chain provides a path for any static charges to dissipate harmlessly into the earth, minimizing the risk of accidents.