Ampere's Law, Cylinders, Solenoid & Toroid
Four identical long solenoids A, B, C and D are connected to each other as shown in the figure. If the magnetic field at the center of A is 3T, the field at the center of C would be: (Assume that the magnetic field is confined with in the volume of respective solenoid).

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Answer: (d)
- Identical solenoids: .
- A carries the full current ; B, C, D are identical and in parallel, so each carries .
- T
- So the answer is (d) 1 T.