This was a MCQ question on one of my Cambridge IGCSE Exams, the answer key said that the resistance would decrease by 16 folds (1/16 less then the previous one), I don't know how they got 16 from? (Apparently, I answered 1/4 and it was wrong)
It doesn't say anything, it was a question from CAMBRIDGE IGCSE
I does in fact mention the length. It states the volume of the putty remains constant as the diameter is increased by twice. For that to be true, the length must also change. Remember that resistance is approximated from resistivity and is inversely proportional to the cross-sectional area of the putty while also being proportional to the putty's length. If the length of the putty decreases while the area increases, the resistance will decrease by the seemingly "too large" factor shown above. Hope this helps.I have a feeling that the length decreases right?