A long solenoid carrying a current produces a magnetic field $B$ along its axis. If the current is d

Question

A long solenoid carrying a current produces a magnetic field $B$ along its axis. If the current is doubled and the number of turns per cm is halved, the new value of the magnetic field is\

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(b) : Magnetic field induction at point inside a long solenoid $l$, having $n$ turns per unit length carrying current $i$ is given by $B=\mu_{0} n i$. If $i ightarrow$ doubled, $n ightarrow$ halved then $B ightarrow$ remains same.\