The lamp L1 marked with 220 V, 100 W and the lamp L2 marked with 220 V, 25 W are connected in series in the same circuit, and they are actually eliminated The lamp L1 marked with 220 V, 100 W and the lamp L2 marked with 220 V, 25 W are connected in series in the same circuit. In order to ensure the safe use of the two lamps, what is the maximum voltage applied at both ends of the circuit

The lamp L1 marked with 220 V, 100 W and the lamp L2 marked with 220 V, 25 W are connected in series in the same circuit, and they are actually eliminated The lamp L1 marked with 220 V, 100 W and the lamp L2 marked with 220 V, 25 W are connected in series in the same circuit. In order to ensure the safe use of the two lamps, what is the maximum voltage applied at both ends of the circuit

The safety current is I (25) = 25W / 220V
R(100)=U*U/R=220*220/100=484
U(100)=IR=(25/220)*484=55
Umax = 220 + 55 = 275

Which is brighter when a 220 V 100 W and a 220 V 25 W bulb are connected in series in a 220 V circuit?

According to P = u ^ 2 / R, the rated voltage of the two bulbs is the same, so the resistance of the bulb with higher rated power is smaller, that is, the resistance of 100W bulb is smaller
According to P = I ^ 2R,
When the current is equal, the greater the resistance, the greater the power consumption
So 25W bulb consumes more power, so it's the brightest

After connecting the "pz220 V -- 15W bulb L1" and the "pz220 V -- 100W bulb L2" in series to the 220 V lighting circuit, the power consumed is P1, P2
If L1 and L2 are connected in parallel in the same lighting circuit, the consumed power is P3 and P4 respectively, what is the relationship between P1, P2, P3 and P4?
Size relation

P4>P3>P1>P2
Because when L1 and L2 are in parallel, 100W > 15W (full load), I (current) is equal to L1 resistance when P4 > P3 is in series
Because L1 is not full load, the sum of its voltage drop and L2 voltage drop is 220 V, so P4 > P3 > P1 > P2

The two bulbs L1 and L2 marked with "220 V, 1000 W" and "220 V, 40 W" are connected in series and then connected in the 220 V lighting circuit. How much power is consumed by L1 and how much power is consumed by L2

The 1000W in "220V, 1000W" is 100W. If not, you can change my following number. The resistance R1 of "220V, 100W" is 220 * 220 / 100 = 484 Ω, and the resistance R1 of "220V, 40W" is 220 * 220 / 40 = 1210 Ω. The current after series connection is I = u / r = 220 / (484 + 1210) = 0.13al1