Question

A solenoid of $1.5 \,m$ length and $4.0 \,cm$ diameter possesses $10$ turns/cm. A current of $5 \,A$ is flowing through it. The magnetic induction a axis inside the solenoid is

• A. $2 \pi \times 10^{-3} T$
• B. $2 \pi \times 10^{-5} T$
• C. $4 \pi \times 10^{-5} T$
• D. $4 \pi \times 10^{-3} T$

Answer 1

Answer: (A)

Magnetic field $B=\mu_{0} n i$
$=4 \pi \times 10^{-7} \times 5 \times 1000$
$=2 \pi \times 10^{-3} T$