初中I.S. - Electricity(1)(過來睇睇啦!!)

2007-03-11 6:57 pm

求求各位,我的功課在明天(mon)就要交啦,幫幫我啦~~

http://hk.geocities.com/cute_maxchangmin/is/0001.jpg
http://hk.geocities.com/cute_maxchangmin/is/0002.jpg
http://hk.geocities.com/cute_maxchangmin/is/0003.jpg

A.The electric current in series circuit:

1.In which case the bulb(s) is/are the brightest? Explain briefly.
2.Do the bulbs in case II have the same brightness? Why?
3.If the electric current in case I is 0.3A,what will be the current in case II & III?

回答 (1)

2007-03-12 6:18 am

✔ 最佳答案

1. case 1 brighter, because the supply voltage apply all at one bulb only, case2 each bulb have half of the voltage, case3 each bulb have one third of the voltage.

2. when they are in series, case2 and case3 each bulb have the same voltage, so they have the same brightness.

3. V divided by R equal to I, the V in three cases are the same, when case1 divided by 1R(1 bulb) get 0.3A, in case2, it need to divided by 2R(2bulbs), so the current will be half less than case2, equal to 0.15A, same reason, in case3, divided by 3, so the current will be 0.1A.

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