Answer to Question #215516 in Electric Circuits for Ravihar

Question

explain why power transmission cables are thicker than your computer power cable

Answer 1

The effective resistance of a conductor is inversely proportional to cross sectional area of a conductor.

Computer power cables usually carry extremely low values of current and therefore, the power transmitted through the computer cable is also minimal.

For high power transmission applications, the cross sectional area of conductor needs to be comparatively larger in order to allow lower resistive path for the electric current flowing through the conductor. This helps in lowering resistive power losses. Also, if the power is transmitted as DC, then the current flows through the entire volume of the conductor. Contrary to it, for AC transmission, there exists a SKIN EFFECT (a phenomenon wherein AC faces higher inductive reactance at the center of the conductor and therefore flows superficially).

Basically, to carry bulk power, the cross sectional area of conductor needs to be higher. Think of the water pipe in your car’s cooling circuit and compare its thickness with that of pipes at a water treatment or sewage treatment plant. You might be able to visualize in a better way.