Verified Solution • 2025–26 Session moderate

QNEET-2022-Ph-426: NEET 2022 Physics - Class 12 NEET-2022-Ph-426 Solution: A long solenoid of radius 1 mm has 100 turns per mm. If 1 A…

A long solenoid of radius 1 mm has 100 turns per mm. If 1 A current flows in the solenoid the magnetic field strength at the centre of the solenoid is 6.28×10−2 T6.28 \times 10^{-2}\ \text{T} 12.56×10−2 T12.56 \times 10^{-2}\ \text{T} 12.56×10−4 T12.56 \times 10^{-4}\ \text{T} 6.28×10−4 T6.28 \times 10^{-4}\ \text{T}

Multiple Choice Options

  • A 6.28 ×\times _ 10 −- _ 2 T
  • B 12.56 ×\times _ 10 −- _ 2 T
  • C 12.56 ×\times _ 10 −- _ 4 T
  • D 6.28 ×\times _ 10 −- _ 4 T

Step-by-Step Verified Solution

We know, magnetic field at centre of solenoid B = _ 0 N l l = _ 0 n l [ n = N l ] = 4 � _ 10 _ 7 _ 100 _ 10 3 _ 1 [ n = 100 10 _ 3 ] = 4 � _ 10 _ 2 T B = 12.56 _ 10 _ 2 T

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