1) Two solenoids are given- 1st has 1 turn per unit length and 2nd has n turns per unit length.Ratio of magnetic fields at their centres is A) n:1 B) 1:n C) 1:n2 D) n2:1 Answer: Option BExplanation: Magnetic field ∝ no. of turns per unit length ∴ Required ratio =1:n
