1) A solenoid 30 cm long is made up of winding 2000 loops of wire on an iron rod whose cross-section is $1.5 cm^{2}$. If the relative permeability of the iron is 6000. What is the self-inductance of the solenoid? A) 1.5 H B) 2.5H C) 3.5 H D) 0.5H Answer: Option AExplanation:As we know , self-inductance of the solenoid $L= \frac{\mu_{r}.\mu_{0} N^{2}A}{I}$ $= \frac{600 \times 4 \pi \times 10^{-7} \times (2000)^{2} \times (1.5)\times 10^{-4}}{0.3}$ $=1.5H$
