Two straight wires of equal length carry the same current of

PHYSICS · Single correct · A Level · Physics · Electricity · Electricity

Problem

3\,\text{A}

. Wire P is copper of diameter

1.0\,\text{mm}

and resistivity

1.7\times10^{-8}\,\Omega\,\text{m}

. Wire Q is nichrome of diameter

0.30\,\text{mm}

and resistivity

1.1\times10^{-6}\,\Omega\,\text{m}

. Ignoring heat losses, what is the nearest value to the ratio of heat produced per unit length in wire P to that in wire Q? (a)

1:100

(b)

10:1

(c)

1:700

(d)

1:10