Resistivity Review

Which factor does not affect resistivity?

• Length

• Mass

• Cross-sectional area

• Temperature

The unit of resistivity is

• Ω/m

• Ω/m²

• Ω.m

• Ω.m²

The nichrome wire has a cross-sectional area of 1.3 × 10^–7 m² . Resistivity of nichrome = 1.1 × 10^–6Ωm and a resistance of 53Ω. The length of the wire is

• 0.63m

• 63m

• 0.0063m

• 6.3m

A copper wire of length 2.5 m and cross-sectional area 2.4 × 10^-7 m² has a resistivity of 1.7x10^-8Ωm. What is the resistance of the wire?

• 1.6x10^-15Ω

• 1.0x10^-14Ω

• 0.18Ω

• 5.6Ω

Resistance of a material would be equal to resistivity when

• l = T

• A = l

• A = T

• l = R

A cylindrical conductor of length l, diameter D, and resistivity ρ has a resistance R. What is the resistance of another cylindrical conductor of length l, diameter D/2 , and resistivity ρ?

• 8R

• 4R

• 2R

• R

A wire of uniform diameter 0.28mm and a length of 1.50m has a resistance of 45Ω. It's resistivity is

• 2.2 x 10^-8Ωm

• 36 Ωm

• 1.8 x 10^-6Ωm

• 3.4 x 10^-7Ωm

Resistivity

• changes with conditions

• relies on dimensions of the material

• inversely proportional to resistance

• a property of the material

Which change decreases the resistance of a piece

of copper wire?

• increasing the wire‛s length

• increasing the wire‛s resistivity

• decreasing the wire‛s length

• decreasing the wire‛s diameter

A wire has a resistance R.

What is the resistance when both the length and radius of the wire are doubled?

• R/4

• R/2

• 2R

• 4R