Physics - circuits

1.我想問點解fuse要接駁去live pin?
ans話因為佢可以isolate the appliance from the high voltage,
點解我唔可以話prevent from too high current?

The question asks for the reason that the fuse has to connect to the live pin.
"Prevent too large current" is the function of the fuse or the purpose in using the fuse.
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2.同埋唔係有voltage--->有potential difference----->有cuurrent嗎??
Yes, if the circuit is complete.
咁唔係應該voltage愈大,current就愈大咩???
但p=VI 點解V同I 會成反比???
V and I are inversely proportional if and only if the power P is kept constant.
If normal circumstances, power consumed is not constant. Therefore, you may use the other forms of the equation:
P = V^2/R or P = I^2.R
where R is the load resistance

單一交流電路是串聯的,,

正常Fuse裝在那裡,,

而斷Fuse時都有效cut斷電路,,

但若Fuse不在Live Pin上,,

雖Cut左電路,,

令它沒有Current,,

但Live Wire仍有220V的電力,,

把Fuse接在Live Wire上,,

燒Fuse時,,

既可令Live Wire沒有電壓,,

也令電路沒有電流,,

所以Fuse接Live Wire是最好~

Prevent From Too High Current係Fuse既功用,,

Isolate The Appliance From The High Voltage,,

係話Fuse阻隔220V同電器既接觸,,

220V->Fuse->電器

若Fuse斷了,,

那220V如何去到電器??

So The Answer Is Isolate The Appliance From The High Voltage..

先有Potential Difference,,

Potential Difference形成Voltage,,

Voltage要形成閉合電路才有Current,,

只有Voltage係不會有Current的~

Ohm's Law :

當電阻不變時,,

電壓上升=電流上升,,,,

V,I,成反比??

因為V大,,

損耗電流少,,

產生功率大,,

好似架空的高壓電纜般~