Question

A solenoid of $1.5m$ length and $2cm$ radius possesses $10$ turns per $cm$. A current of $5A$ is flowing through it. The magnetic field induction inside solenoid is:

• A. $0.13\pi \times {10}^{-3}T$
• B. $2\pi \times {10}^{-3}T$
• C. $2.3\pi \times {10}^{-4}T$
• D. $0.13\pi \times {10}^{2}T$

Answer 1

The correct option is B $2\pi \times {10}^{-3}T$

In a solenoid $B={\mu }_{0}ni={\mu }_0\frac{N}{l}i=4\pi \times {10}^{-7}\times \frac{10}{1.5}\times 5$

$=0.13\pi \times {10}^{-3}T$