If number of turns per unit length in a solenoid is tripled, the self inductance of solenoid will

Step-by-step solution

Self-inductance of a solenoid is given by aligned & L = ₀ ~N ^2 ~A l & ~L ~N ^2 & ~L ₁ ~L ₂ = ( N ₁ ~N ₂ )^2 & ~L ~L ₂ = ( N 3 ~N )^2 & ~L ₂=9 ~L aligned