有一個 rating 220V,100W and 兩個 raing 110V,60W.
Question:
Paul suggests inserting a 1A fuse into circuit to protect three bulbs.
Is it suitable?
Answer:
working current = 220/220=1A
The resistance of the non-operating bulbs is smaller than the working resistance as the bulbs are much cooler when they are off.
The current is larger than 1A when the bulbs are just turned on.
not suitable
MY QUESTION
唔係好明個answer,佢話因為resistance 實際上大d,因為temp.高d
但係resistance 大,current 唔係應該細左?可唔可以解釋吓??
domestic electricity
2006-11-06 2:36 am
回答 (2)
2006-11-08 11:05 pm
✔ 最佳答案
用 I V = Power 是計出 rated current，即是燈泡正常運作中所須總額定電流量。亦即是1A。如剛開燈時的電阻較開燈後為少，則電流於剛開燈時便會超過1A，用1A fuse 便有機會燒。
2006-11-06 2:41 am
In my understanding, the answer means that as the bulb has just turn on, the coil is cool.
When the temperature is low, the resistance is low.
As at the beginning, the bulb is not heated, as that moment, the resistance is smaller than the expected value(the calculated value). The current pass through is larger than 1A. The fuse therefore melts and breaks the circuit.
Hence, 1A fuse is not suitable.
When the temperature is low, the resistance is low.
As at the beginning, the bulb is not heated, as that moment, the resistance is smaller than the expected value(the calculated value). The current pass through is larger than 1A. The fuse therefore melts and breaks the circuit.
Hence, 1A fuse is not suitable.
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