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If a lamp marked "220 V & nbsp; & nbsp; 40 W" is connected to 110 V power supply, the actual power of the bulb is () A. 40WB. 30WC. 20WD. 10W
∵ P = u2r, ∵ bulb resistance R = U2 rated, P rated = (220 V) 240 w = 1210 Ω, when the voltage is 110 V, the actual power of the bulb: P real = U2 real, r = (110 V) 21210 Ω = 10 W; so D
10. One incandescent lamp with rated value of 220 V, 60 W and 110 V, 40 W respectively
(1) Which light is on when they are connected in series to 220 V power supply? Why? (2) which light is on when they are connected in parallel to 48 V power supply? Why?
1) After connecting them in series, the 40W incandescent lamp on the 220 V power supply lights up because of the high voltage. 2) when connecting them in parallel to the 48 V power supply, the 60W incandescent lamp lights up because of the high current
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