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Three unequal resistor in parallel are equivalent to a resistance `1Omega` If two of them are in the ratio 1:2 and if no resistance value is fractional the largest of the three resistance in ohm isA. `4`B. `5`C. `6`D. `10` |
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Answer» Correct Answer - c Given, `(R_(1))/(R_(2)) =(1)/(2) or R_(2) = 2R_(1)` The equivalent resistance of parallel combination is `(1)/(R ) = (1)/(R_(1)) + (1)/(R_(2)) + (1)/(R_(3))` `(1)/(R_(1)) + (1)/(2R_(2)) + (1)/(R_(3))= (3)/(2R_(1)) + (1)/(R_(3))` or `(1)/(R_(3)) = (1)/(R )-(3)/(2R_(1)) = (1)/(1)- (3)/(2R_(1))` or `1 = R_(3) = (3R_(3))/(2R_(1))` `R_(3) = (3R_(3))/(2R_(1))` Since no resistance value is fractional, hence minimum value of `(R_(1))/(R_(2)) = (2)/(3)` So `R_(2) = 1+ (3)/(2)xx(2)/(3) = 1+1 = 2 Omega` and `R_(1) = (3R_(3))/(2) = (3xx2)/(2) = 3 Omega` `:.` Maximum resistance value is of `R_(2) = 2R_(1) = 2 xx 3 = 6 Omega` |
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