Question

A wire has a resistance of 16 ohm.it is melted and drawn into a wire of half its length calculate the resistance of new wire

Answer 1

Heya friend here is your answer
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resistance of new wire :

resistance is directly propotional to teh length of the conductor 

half length = 2 double resistance

= 16 x 2 

= 32 ohm !!

Answer 2

R1 = 1 OhmR2 = ?L1 = LL2 = 2L1 = 2LNow, when the wire is melted and recast into a wire of twice length, its volume will remain unchangedSo, L1A1 = L2A2      L1A1 = 2L1A2          A2 = A1/2 ------------------------ (1)Now, resistance R = RHO*L/AR1 = RHO * L1/A1R2 = RHO * L2/A2R1/R2 = RHO(L1/A1)/ RHO(L2A2) = LIA2/L2A1From equation 1 R1/R2 = L1A1/2*2L1A1 = 1/4R2 = 4R1 = 16*4 = 64 OhmTherefore, change in resistance = R2-R1 = 64-16 = 48 OhmPERCENTAGE CHANGE IN RESISTANCE = 48/16 = 3*100 = 300%

[Thank You]