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Current Electricity — JEE physics STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 ScienceJEE physicsCurrent Electricity1 Mark
MCQ
Consider the circuit shown in the figure. The current $I_3$ is equal to
Image
  • ✓
    $5 \mathrm{amp}$
  • B
    $3 \mathrm{amp}$
  • C
    $-3 \mathrm{amp}$
  • D
    $-5 / 6 a m p$
✓

Answer

Correct option: A.
$5 \mathrm{amp}$
For same material and same length$\frac{R_2}{R_1}=\frac{A_1}{A_2}=\frac{3}{2}$
$\Rightarrow R_2=3 R_1$
Resistance of thick wire $R_1=10 \Omega$
$\therefore$ Resistance of thin wire $R_2=30 \Omega$
Total resistance in series $=10+30=40 \Omega$

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