Importance of Low Resistance per Unit Length in Electrical Cables

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SUMMARY

The discussion emphasizes the critical importance of low resistance per unit length in electrical cables, particularly for long connections to appliances. A low resistance allows for a larger current to flow, which is essential for the proper operation of electrical devices. Additionally, maintaining low resistance minimizes energy loss through heat dissipation, enhancing overall efficiency. The conversation also highlights the relationship between cable resistance and the Thevenin equivalence circuit, underscoring the need for low resistance to reduce energy loss.

PREREQUISITES
  • Understanding of electrical resistance and its impact on current flow
  • Familiarity with Thevenin's theorem and equivalence circuits
  • Knowledge of power dissipation formulas, specifically I²R
  • Basic principles of electrical appliances and their operational requirements
NEXT STEPS
  • Research Thevenin's theorem and its applications in circuit analysis
  • Explore the relationship between resistance, current, and voltage in electrical systems
  • Study power dissipation in electrical components and methods to minimize it
  • Investigate materials and designs that contribute to low resistance in electrical cables
USEFUL FOR

Electrical engineers, students studying circuit theory, and professionals involved in designing or optimizing electrical systems will benefit from this discussion.

Kushal
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Homework Statement



Some electrical appliances are used with long cables to connect to them to the electrical supply. State and explain 2 reasons why these cables should have a low resistance per unit length.


The Attempt at a Solution



well for the long cables, a low resistance per unit length would mean a low resistance for the cable itself. a larger current will flow.

i cannot see any advantage in that. rather the cables will be less safe with a larger current. the power dissipated, I2R, will be larger, hence less efficient.

so i don't know...
 
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Kushal said:
Some electrical appliances

well for the long cables, a low resistance per unit length would mean a low resistance for the cable itself. a larger current will flow …

Hi Kushal! :smile:

No … you've completely ignored the resistance of the appliance

it is (mostly) that resistance which determines the current, I.

So the current is more-or-less fixed by the appliance.

So the effect of the resistance of the wire is … ? :smile:
 
yeah you're right, i completely ignored that. a small current might not be able to operate the appliance.

errmm i still can't find the second reason... a hint would be great...lol

thnks
 
Kushal said:
yeah you're right, i completely ignored that. a small current might not be able to operate the appliance.

errmm i still can't find the second reason... a hint would be great...lol

thnks

It looks like you were on to the second drawback in your first try.
 
EDIT: Nevermind, got resistance confused with impedance.

Anyway, yes you were close. Think of the Thevenin equivalence circuit.
 
Last edited:
You guys have completely forgot that the higher the voltage of the current moving through the mains power the less energy that is lost through heat and for that to work the resistance must be low.
 

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