Physics - Current Electricity Question with Solution | TestHub

The resistances can be calculated as

$R_A=R+\frac{R}{2}=\frac{3R}{2}$

For second circuit

$$\begin{gathered} \frac{1}{R_B}=\frac{1}{2R}+\frac{1}{R}=\frac{3}{2R} \\ \Rightarrow R_B=\frac{2R}{3} \end{gathered}$$

For third circuit

$R_C=\frac{R}{3}$

For fourth circuit

$R_D=3R$

The formula for power is given by $P=I^{2}R$.

Clearly, 

$P_D>P_A>P_B>P_C$