Now consider the cross-sectional-area, (c.s.a.) Let (r1 = 1Ω) If the c.s.a. is doubled in size then: Rt = ½ = 0.5Ω (Remember: resistance decreases) If the c.s.a. is increased six times then: Rt = ⅙ = 0.1667Ω
Q2
If a conductor has a resistance of 17.8µΩ/mm, determine the resistance of 10m of this conductor if the c.s.a. is 1.5mm²
Answer:
CONDUCTORS Remember, conductor resistance is affected by conductor length, cross-sectional area and temperature. Q3
Complete the following using either the term ‘increases’ or ‘decreases’:
a) The resistance of a conductor .............................................. with increasing length b) The resistance of a conductor .............................................. with decreasing c.s.a. c) The resistance of a conductor .............................................. with increasing temperature
INSULATION Q4
Complete the following using either the terms ‘increases’, ‘decreases’ or ‘remains the same’
a) The insulation resistance of a cable .............................................. with increased length b) The insulation resistance of a cable .............................................. with increasing c.s.a. c) The insulation resistance of a cable .............................................. with decreasing length
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E X E RC I SE I AU TU MN 2019 I SPA RKS
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