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Q12 (NDA-II/2022) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Electricity and magnetism

Which one of the following statements regarding a current-carrying solenoid is not correct?

Result
Your answer: —  Â·  Correct: D
Explanation

A current-carrying solenoid generates a magnetic field that is uniform and strong inside the coil, with field lines running parallel to the axis [1]. It behaves like a bar magnet, exhibiting distinct north and south poles [2]. The magnetic field strength (B) is directly proportional to the current (I) flowing through it, as defined by the relation B = μ₀nI; thus, increasing the current increases the field strength [1]. However, statement 4 is incorrect because inserting a soft iron bar significantly increases the magnetic field strength [1]. Soft iron has high magnetic permeability, which concentrates the magnetic flux and magnetizes the core, transforming the solenoid into a much stronger electromagnet [2]. Therefore, the claim that the magnetic field remains the same is false.

Sources

  1. [1] Science , class X (NCERT 2025 ed.) > Chapter 12: Magnetic Effects of Electric Current > 12.2.4 Magnetic Field due to a Current in a Solenoid > p. 201
  2. [2] Science , class X (NCERT 2025 ed.) > Chapter 12: Magnetic Effects of Electric Current > What you have learnt > p. 206
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SIMILAR QUESTIONS

NDA-I · 2019 · Q47 Relevance score: 5.50

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