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यदि किसी तार को खींचकर उसकी लम्बाई दोगुनी कर दी जाये , तो उसका प्रतिरोध कितना हो जायेगा ? |
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Answer» ` :. pir_(1)^(2)l_(1) = pir_(2)^(2)l_(2)` या ` (l_(1))/(l_(2))=((r_(2))/(r_(1)))" "`…(1) सूत्र `R=(rhol)/(A)` से ` (R_(1))/(R_(2))=(l_(1))/(A_(1)) xx (A_(2))/(l_(2)) = (l_(1))/(l_(2)) xx (pir_(2)^(2))/(pir_(1)^(2))` या ` (R_(1))/(R_(2)) =(l_(1))/(l_(2)) xx(r_(2)^(2))/(r_(1)^(2))` समी (1 ) में मान रखने पर , `(R_(1))/(R_(2))=((l_(1))/(2l_(1)))^(2)=1/4` या `R_(2) = 4R_(1)` |
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