常識問題(2題)幫一幫

Definition Of Short Circuit :

Since The Resistance Of A Circuit Is Very Very Low In Short Circuit,
By The Ohm's Law,Low Resistance Produce High Current,High Current Produce Heat,Large Of Heat Can Distroy The Cable Of Explosion.

電線的外層一般用甚麼物料製成?為甚麼?

Plastic,
Since The Resistivity Of Plasric Is High,It Means The Resistance Of Plastic Is High,It Can Insulate The Voltage To Avoide Short Circuit.

導師說 : 短路電流無限大，短路即電路未通過負載即返回路，那一點通過電可以很大而造成極短時間極高溫，甚至燒毀電線膠的外皮及附近的物件引致火警。

電線的外皮用膠來造，因為它是不導電 bad conductor 。

1.因為能量left at 電線and became too hot then 火災
2.膠 因為成本低，又安全，而膠又不導電