【Daily Topic】【Electrical Edition 20160424】
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This post was last edited by hesonchang214 on 2016-4-25 at 15:27. Remember to hide the answers when replying! Participation reward: 2 Wealth. Reward for correct answer: 9 wealth. There is a power source with an electromotive force of 225V and an internal resistance of 2.5Ω. The external circuit consists of several lamps rated at 220V and 40W each. To ensure that the lamps shine properly, the maximum number of lamps that can be used simultaneously is ( ). A, 5 ； B, 11 ； C, 25 ； D, 40.
There is a power source with an electromotive force of 225V and an internal resistance of 2.5Ω. The external circuit consists of several lamps rated at 220V and 40W each. To ensure that the lamps shine properly, at most (B) lamps can be used simultaneously. A, 5 ； B, 11 ； C, 25 ； D, 40.
B, 11； ~~~~~~~~
There is a power source with an electromotive force of 225V and an internal resistance of 2.5Ω. The external circuit consists of several lamps rated at “220V, 40W”. To ensure that the lamps shine properly, at most (b) lamps can be used simultaneously
B: The internal resistance of the 11V power supply creates a voltage drop of 5 volts, so the current in the main circuit is 2A. The total power in the external circuit is 220*4=880W; therefore, 11 lights can be used simultaneously