short circult 同 burn out 有咩分別

2007-04-18 8:41 am
┌──│ l──┐
│─A ─Ω──│
└──V───┘

如果上面個LIGHT BULB form normal to short cuircult
reading of ammeter 同voltmeter個reading 會變成點( increase decrease 定 變 zero 等等)
咁如果唔係to short circult 係 burn out 既話 又會點變

同埋如果個圖係

┌──│l───┐ 個LIGHT BULB form normal to short cuircult
A " " " " " " " " " " │ reading of ammeter 同voltmeter個reading 會變成點 ├───Ω───┤ ( increase decrease 定 變 zero 等等)
└──V────┘ 咁如果唔係to short circult 係 burn out 既話 又會點變
更新1:

""" 係space 唔使理

回答 (1)

2007-04-19 3:08 am
✔ 最佳答案
┌──│ l──┐
│─A ─Ω──│
└──V───┘
if the light bulb is shorted, very large current will pass through the ammeter (since the shorted light bulb has no resistance), the ammeter will burn out. No reading is shown by ammeter. The voltmeter across the cell measures the cell emf (potential difference across the cell)
if the light bulb burns out, the circuit is open and no current pass through the ammeter. No reading is shown by ammeter too. The voltmeter again across the cell measures the cell emf.

┌──│l───┐
A │
├───Ω── ┤
└──V─── ┘
if the light bulb is shorted, very large current will pass through the ammeter too, the ammeter will burn out. No reading is shown by ammeter.
But at this time the voltmeter measures the p.d. across a wire, so its reading is zero.
if the light bulb burns out, in fact no current will be drawn as the resistance of voltmeter is infinitely large. if it is not an ideal voltmeter, extremely small current will be drawn but it can hardly be shown by the ammeter, it seems to have no resding.
參考: myself


收錄日期: 2021-04-29 19:24:48
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070418000051KK00180

檢視 Wayback Machine 備份