Current Electricity Ques 51

  1. For the circuit shown with $R _1=1.0$ $ \Omega, R _2=2.0 $ $\Omega, E _1=2$ $ V$ and $E _2=E _3=4 $ $ V$, the potential difference between the points $a$ and $b$ is approximately (in volt)

(2019 Main, 8 April I)

(a) $2.7$

(b) $2.3$

(c) $3.7$

(d) $3.3$

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Answer:

Correct Answer: 51.(d)

Solution:

  1. Given circuit is

Above circuit can be viewed as

This is a parallel combination of three cells or in other words, a parallel grouping of three cells with internal resistances.

So, $\quad V _{a b}=E _{eq}=\frac{I _{eq}}{r _{eq}}=\frac{\frac{E _1}{r _1}+\frac{E _2}{r _2}+\frac{E _3}{r _3}}{\frac{1}{r _1}+\frac{1}{r _2}+\frac{1}{r _3}}$

$ =\frac{\frac{2}{2}+\frac{4}{2}+\frac{4}{2}}{\frac{1}{2}+\frac{1}{2}+\frac{1}{2}}=\frac{10}{3} V \approx 3.3 V $



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