A "6V, 0.5A" small bulb connected in series with a 24 ohm resistor is connected to a power supply, which can make the small bulb work normally. What is the power supply voltage? (with the knowledge solution of elementary 2)

A "6V, 0.5A" small bulb connected in series with a 24 ohm resistor is connected to a power supply, which can make the small bulb work normally. What is the power supply voltage? (with the knowledge solution of elementary 2)

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In normal operation, the current passing through the small bulb is 0.5A, because it is in series, so the resistance is also 0.5A, so the voltage at both ends of the resistance is u = I * r = 0.5 * 24 = 12V, because the total voltage in the series circuit is the sum of the voltages of all electrical appliances, so the power supply voltage is 6 + 12 = 18V
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A light bulb is printed with "PZ & nbsp; 220 & nbsp; 25". How much resistance does it have when it works normally? If it is connected to a 110V circuit, what is the actual power consumption? Compared with the circuit connected to 220 V, is it brighter or darker? Please explain the reason

(1) ∵ P = u2r, ∵ bulb resistance R = u2p = (220V) 225W = 1936 Ω, (2) when the voltage is 110V, the actual power of the bulb: P = U2, r = (110V) 21936 Ω = 6.25w; (3) when the bulb is connected to the 110V circuit, the actual power is 6.25w, when it is connected to the 220V circuit, the actual power of the bulb is 25W, and the brightness of the bulb depends on the actual power of the bulb, so the bulb is dark when it is connected to the 110V circuit A: the resistance of the bulb is 1936 Ω; when the bulb is connected to the 110V circuit, the actual power of the bulb is 6.25 W; when the bulb is connected to the 110V circuit, it is darker because the actual power of the bulb is small