Two heaters A and B have power rating of 1 kW and 2 kW, respectively. Those two are first connected in series and then in parallel to a fixed power source. The ratio of power outputs for these two cases is:

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(4) 2 : 9. At the rated voltage V: R_A=(V²)/(1000) and R_B=(V²)/(2000), so R_A=2R_B. Series: Pₛ=(V²)/(R_A+R_B)=(V²)/(3R_B). Parallel: Pₚ=1+2=3 kW =(V²)/(R_A)+(V²)/(R_B)=(3V²)/(2R_B). (Pₛ)/(Pₚ)=(1/3)/(3/2)=2/9.

Two heaters A and B have power rating of 1 kW and 2 kW, respectively. Those two are first connected in series and then in parallel to a fixed power source. The ratio of power outputs for these two cases is:

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