Current Electricity - Result Question 109

114. Five resistances have been connected as shown in the figure. The effective resistance between $A$ and $B$ is

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(a) $\frac{14}{3} \Omega$

(b) $\frac{20}{3} \Omega$

(c) $14 \Omega$

(d) $21 \Omega$

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Answer:

Correct Answer: 114. (a)

Solution:

  1. (a) It is a balanced wheatstone bridge $(\because \frac{3}{4}=\frac{6}{8})$, so the $7 \Omega$ resistance is ineffective. Equivalent resistance of $3 \Omega$ and $4 \Omega=3+4$ $=7 \Omega$ (series)

Equivalent resistance of $6 \Omega$ and $8 \Omega=6+8$

$=14 \Omega$ (series)

Equivalent resistance of $7 \Omega$ and $14 \Omega$ (parallel)

$=\frac{7 \times 14}{7+14}=\frac{14}{3} \Omega$