Question
A wire of resistance 160 is melted and drawn in wire of one-fourth of its length. The new resistance of the wire will be
BITSAT
Physics
Current Electricity
2024
BITSAT 2024 (Memory Based Paper 2)
BITSAT Physics Question (2024) — Solution
Options
- A. 10
- B. 640
- C. 40
- D. 16
Answer
A. 10
Step-by-step solution
Let Initial length =l_1 Final length =l_2 Initial area = A _1 Final area =A_1 Volume remains same A _1 l _1= A _2 l _2 ~A _1 l _1= A _2 l _1 4 4 ~A _1= A _2 Initial resistance, R _1= l_1 A_1 =160 (given) Final resistance, R _2= l _2 ~A _2 R _2 R _1 = l _2 ~A _1 ~A _2 l _1 = l_1 4 ~A _1 4 ~A _1 l_1 R_2= 1 16 R_1= 1 16 160=10
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