resistance per unit length

[Kushal]

1. The problem statement, all variables and given/known data

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.


3. 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....

[tiny-tim]

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:

[Kushal]

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

[LowlyPion]

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.

[Topher925]

EDIT: Nevermind, got resistance confused with impedance.

Anyway, yes you were close. Think of the Thevenin equivalence circuit.