A straight wire of unstretched length L has an electrical resistance R. The area of the cross-section A of the wire may be assumed to be constant.
State the relation between R, L, A and the resistivity ρ of the material of the wire.
Measurements made for a sample of metal wire are shown in Table 1.1.
Table 1.1
Quantity | Measurement |
resistance diameter length |
6.1 Ω 0.44 mm 1390 mm |
State the most appropriate instrument to use to measure
Show that the resistivity of the metal is 6.67 × 10–7 Ω m.
State and explain what would happen to the resistivity of the wire if the diameter was doubled.
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