Question
A long straight wire of radius a carries a steady current 1 . The current is uniformly distributed across its cross section. The ratio of the magnetic field at a 2 and 2a from axis of the wire is:
BITSAT
Physics
Magnetic Effects of Current
2024
BITSAT 2024 (Memory Based Paper 2)
BITSAT Physics Question (2024) — Solution
Options
- A. 1: 4
- B. 4: 1
- C. 1: 1
- D. 3: 4
Answer
C. 1: 1
Step-by-step solution
Magnetic field due to straight wire, B= _0 I 2 r Magnetic field at a 2 is, B _ a / 2 = _0 I 2 ( a / 2) B _ a / 2 ~B _ 2 a = 1 1 =1: 1
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