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Current Electricity question

2023 · 13 Apr · Shift 1 · Q59
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Current Electricity question

2023 · 13 Apr · Shift 1 · Q59

JEE MainPhysicsCurrent ElectricityMCQ+4 / −1
Different combination of 3 resistors of equal resistance R\mathrm{R}R are shown in the figures. The increasing order for power dissipation is: JEE Main 2023 (Online) 13th April Morning Shift Physics - Current Electricity Question 89 English
  1. A
    PB<PC<PD<PA\mathrm{P}_{\mathrm{B}}\lt \mathrm{P}_{\mathrm{C}}\lt \mathrm{P}_{\mathrm{D}}\lt \mathrm{P}_{\mathrm{A}}PB​<PC​<PD​<PA​
  2. B
    PC<PB<PA<PD\mathrm{P}_{\mathrm{C}}\lt \mathrm{P}_{\mathrm{B}}\lt \mathrm{P}_{\mathrm{A}}\lt \mathrm{P}_{\mathrm{D}}PC​<PB​<PA​<PD​
  3. C
    PC<PD<PA<PB\mathrm{P}_{\mathrm{C}}\lt \mathrm{P}_{\mathrm{D}}\lt \mathrm{P}_{\mathrm{A}}\lt \mathrm{P}_{\mathrm{B}}PC​<PD​<PA​<PB​
  4. D
    PA<PB<PC<PD\mathrm{P}_{\mathrm{A}}\lt \mathrm{P}_{\mathrm{B}}\lt \mathrm{P}_{\mathrm{C}}\lt \mathrm{P}_{\mathrm{D}}PA​<PB​<PC​<PD​
View written solutionFree

Correct answer: D: $$P_A<P_B<P_C<P_D$$

  1. Let the same potential difference VVV be applied across each combination.

  2. Total power dissipated by a combination is P=V2ReqP=\frac{V^2}{R_{\text{eq}}}P=Req​V2​ So, smaller equivalent resistance means larger power.

  3. Now compute equivalent resistance for each arrangement (standard 3-resistor combinations of equal resistance RRR):

    • A: All three in series RA=3RR_A=3RRA​=3R PA=V23RP_A=\frac{V^2}{3R}PA​=3RV2​

    • B: Two in parallel, then in series with one resistor RB=R+R⋅RR+R=R+R2=3R2R_B=R+\frac{R\cdot R}{R+R}=R+\frac{R}{2}=\frac{3R}{2}RB​=R+R+RR⋅R​=R+2R​=23R​ PB=V2(3R/2)=2V23RP_B=\frac{V^2}{(3R/2)}=\frac{2V^2}{3R}PB​=(3R/2)V2​=3R2V2​

    • C: Two in series, then in parallel with one resistor RC=(2R)R2R+R=2R3R_C=\frac{(2R)R}{2R+R}=\frac{2R}{3}RC​=2R+R(2R)R​=32R​ PC=V2(2R/3)=3V22RP_C=\frac{V^2}{(2R/3)}=\frac{3V^2}{2R}PC​=(2R/3)V2​=2R3V2​

    • D: All three in parallel RD=R3R_D=\frac{R}{3}RD​=3R​ PD=V2R/3=3V2RP_D=\frac{V^2}{R/3}=\frac{3V^2}{R}PD​=R/3V2​=R3V2​

  4. Compare powers: PA=V23R,PB=2V23R,PC=3V22R,PD=3V2RP_A=\frac{V^2}{3R},\quad P_B=\frac{2V^2}{3R},\quad P_C=\frac{3V^2}{2R},\quad P_D=\frac{3V^2}{R}PA​=3RV2​,PB​=3R2V2​,PC​=2R3V2​,PD​=R3V2​

    Hence the increasing order is PA<PB<PC<PDP_A<P_B<P_C<P_DPA​<PB​<PC​<PD​

  5. Checking options: This matches Option D.

  6. Comparison with stored answer: Stored answer is B, but the correct order from equivalent resistances is D. So the stored answer appears incorrect.

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