Current Electricity

JEE Main level, single correct, medium

238 of 380

Question 238 of 380

Different combination of 33 resistors of equal resistance RR are shown in the figures. The increasing order for power dissipation is:
(A)
(B)
(C)
(D)

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Answer: (C) PC<PB<PA<PD{P}_{C}\lt {P}_{B}\lt {P}_{A}\lt {P}_{D}

The resistances can be calculated as
RA=R+R2=3R2{R}_{A}=R+\dfrac{R}{2}=\dfrac{3R}{2}
For second circuit
1RB=12R+1R=32R⇒RB=2R3\dfrac{1}{{R}_{B}}=\dfrac{1}{2R}+\dfrac{1}{R}=\dfrac{3}{2R} \Rightarrow {R}_{B}=\dfrac{2R}{3}
For third circuit
RC=R3{R}_{C}=\dfrac{R}{3}
For fourth circuit
RD=3R{R}_{D}=3R
The formula for power is given by P=I2RP={I}^{2}R.
Clearly,
PD>PA>PB>PC{P}_{D}\gt {P}_{A}\gt {P}_{B}\gt {P}_{C}

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