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A uniform wire of resistancee 100Ω is melted and recast into wire of length double that of theoriginal. What would be the resistance of the new wire formed? |
| Answer» RM wire of resistance 100Ω is melted and recast into wire of length double that of the original. so, volume of wire remains constant.let V. we know, R = ρl/A or, R = (ρl × l)/(A × l) = ρl²/V [ where V = Al , volume = cross SECTIONAL area × length ] now, R is directly PROPORTIONAL to square of length.i.e., R1/R2 = l1²/l2² here, R1 = 100Ω, l1 = l and l2 = 2l so, (100)/R2 = l²/(2l)² = 1/4 or, R2 = 100 × 4 = 400 Ωhence, new resistance of wire will be 400Ω. | |