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A uniform wire resistance `20 Omega` having resistance `1 Omega ` is bent in the forms of a circuit if the equal - valent resistance between A and B is `1.8 Omega ` then length of the shorter section is A. `1.8 m`B. `2 m`C. `3.6 m`D. `4 m` |
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Answer» Correct Answer - b Let resistance of shorter part `AB` be `x` the total resistance is `20 Omega` the resistance of longer `AB` part is `(20- x)` between point A and B the two resistance `x` and their equivalent resistance in `R_(eq) = ((20 - x) xx x)/((20 - x) xx x) = 1.8` On solving get `x = 2 Omega` Thus, length of the shorter section `= 2 xx 1 = 2m` |
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