Does a fuse wire have a high or a low resistivity?

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There are two different aspects of your question.

First one is that the resistivity of all metals in between 1.5*10^-8 ohm*m and 10*10^-8 ohms*m. For a fuse wire which is about 5 cm long and has about 1 mm^2 surface area its resistance is between 0.00075 ohm and 0.005 ohm (`R=rho*l/S` , where R is resistance, `rho` is resistivity, l is wire length and S is surface area). In a physical way of speaking it means all fuse wires have about the same resistance.

Second aspect is that for a fuse to melt you want it to heat as fast as possible from the current through it. The heating power of a wire having resistance R from a current I is

`P= I^2*R` , which tells you that the higher the resistance of the wire, the faster it heats from the current and the faster it melts down.

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