JEE MAIN - Physics (2021 - 27th August Evening Shift - No. 24)
The ratio of the equivalent resistance of the network (shown in figure) between the points a and b when switch is open and switch is closed is x : 8. The value of x is ___________.
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Answer
9
Explanation
$${R_{eq\,open}} = {{3R} \over 2}$$
$${R_{eq\,closed}} = 2 \times {{R \times 2R} \over {3R}} = {{4R} \over 3}$$
$${{{R_{eq\,open}}} \over {{R_{eq\,closed}}}} = {{3R} \over 2} \times {3 \over {4R}} = {9 \over 8}$$
$$\therefore$$ $$x = 9$$
$${R_{eq\,closed}} = 2 \times {{R \times 2R} \over {3R}} = {{4R} \over 3}$$
$${{{R_{eq\,open}}} \over {{R_{eq\,closed}}}} = {{3R} \over 2} \times {3 \over {4R}} = {9 \over 8}$$
$$\therefore$$ $$x = 9$$
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