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A copper wire has a diameter 0.5 mm and resistivity 1.6X 10 ohmm.(i) What will be the length of this wire tomake the resistance of 12 ohm.(i) How much will be the resistance of anothercopper wire of some length but half thediameter ?? |
| Answer» EXPLANATION:diameter = 0.5 mm converting it into m0.5× 1/1000=0.0005 mNow (1)R=rho L/a12=16 ×l/0.0005(Where l is the length of WIRE we have to find)L=12×0.0005//16L=3/4×0.0005L=3×0.000125L=0.000375 mOr 0.375 mm(2)Diameter is halfA = PIE (d/2)^2A=pie d sq//4 Now new areaA'= pie (d/2×1/2)^2A'=pie d sq//16Or A'= A/4Now if are is 1/4 then r will be 4 times as it is indirectly PROPORTIONAL to aSo the answer is= 12×4=48 ohm Hope it help | |