Question

Why a ruler is not used to measure the thickness of a wire?

Answer 1

The ruler that we use in routine can measure length in milimetres only, it can't measure length smaller than 1 mm correctly. Thickness of wire can be less than that hence it's not used for measuring it

Answer 2

heya answer is here.......

♧The wrapping approach is the classic method (and can give you an answer in "gauge" directly if you care for that sort of thing) and can be very accurate if combined with either a vernier caliper or a micrometer