The core increases the field because:

  1. it carries extra current
  2. the magnetic domains in the iron line up with the solenoid's field
  3. it heats up
  4. it is charged
Answer

B) the magnetic domains in the iron line up with the solenoid's field

Domain alignment. SLO P-09-E-36 · Knowledge

Physics MCQ · More Magnetism and Electromagnetic Induction MCQs · Practise