The p.d. V across a wire of length l is given by the formula V = 4IpI/d² where d is the diameter of the wire, ρ is the resistivity and there is a current I in the wire. Which quantity provides the largest contribution to the percentage uncertainty in V?

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Quantity Value of quantity Absolute uncertainty А 1/ cm 250 ±10 В d/mm 1.4 ±0.1 C p/2 m 1.5 x 10-8 +0.2 x 10-8 D I/ A 2.0 +0.2 Table P1.12