An electric current produces a magnetic field - Online practice 3

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Paper electromagnet comparison: Coil A: 40 turns, 0.2 A, air core; B: 40 turns, 0.2 A, suitable iron core. Intended factor: core material. An investigation would measure the same defined magnetic outcome under controlled conditions. These numbers describe models, not safe construction instructions. Real coils require a qualified adult, current limits and heating precautions; never use mains electricity.