點搞
When a nichrome wire of length L and diameter d is connected to a dry cell, the current flowing through the wire is 0.6A. If another nichrome wire of length 3L and diameter 2d is connected to the same cell, what will be the current flowing throuh wire?
A. 0.3A
B. 0.8A
C. 1.2A
D. 1.8A
點計個答案係B?
仲有
A series of 20 light bulbs each has a rating of "11V, 4w" is connected to a 220V power supply. One of the bulbs burns out. Kenneth replaces it with a new bulb, which is also marked 4W. But the new bulb appears dimmer than the other bulbs. Which of the following statements are correct?
(1) The resistence of the news bulb is lower than that of the other bulbs.
(2) The voltage across the new bulb is less than that across eact of the other bulbs.
(3) The new bulb is designed to work at a low voltage.
A. (1) and (2)
B. (1) and (3)
C. (2) and (3)
D. (1), (2) and (3)
點計個答案係D?
唔該晒
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本帖最後由 真田 於 2009-1-4 14:12 編輯 ]
