NEET Questions Solved

PMT - 1995

Two wires of same metal have the same length but their cross-sections are in the ratio 3 : 1. They are joined in series. The resistance of the thicker wire is 10 Ω. The total resistance of the combination will be 

(1) 40 Ω

(2) 403Ω

(3) 52Ω  

(4) 100 Ω

(1) For same material and same length

R2R1=A1A2=32R2=3R1

Resistance of thick wire R1=10Ω

∴ Resistance of thin wire R2=30Ω

Total resistance in series = 10 + 30 = 40 Ω 

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