“6v 6w”,的灯泡电阻为 R1=U额²/P额=(6V)²/6W=6Ω
“6v 3w”,的灯泡电阻为 R2=(6V)²/3W=12Ω
串联电流相同 I1=I2
根据P=I²R
P1/P2=I1²R1/I2²/R2=R1/R2=1/2