A 50 cm long solenoid has winding of 400 turns. What current must pass through it to produce a magnetic field of induction $4 \pi \times 10^{-3} \mathrm{~T}$ at the centre?
- A
10.5 A
- B
12.5 A
- C
25.0 A
- D
20.0 A
✓ Correct answer: B
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