Module 4 - 4.2.4 Resistivity

Question 1

Resistance of a wire depends on 3 things

Answer 1

• length (longer = higher)
• cross-sectional area (bigger = smaller)
• material (metal = low)

Question 2

Resistivity changes with

Answer 2

temperature

Question 3

Resistivity Equation

Answer 3

pT = p0 [1+alpha(T-T0)]

Question 4

Pure Metals
- temp coefficient
- change in resistance with temperature

Answer 4

• temp coefficient = +ve
• resistance increases with increasing temperature

Question 5

Carbon, Silicon, Germanium
- temp coefficient
- change in resistance with temperature

Answer 5

• temp coefficient = -ve
• resistance decreases with increasing temperature

Question 6

Some Metal Alloys
- temp coefficient
- change in resistance with temperature

Answer 6

• temp coefficient = very close to 0
• resistance hardly changes with changes in temperature