Question

A long solenoid has 200 turns per cm and carries a current of 2.5 amps. The magnetic field at its centre is (${\mu }_0=4\pi \times {10}^{-7}weber/amp-m$)

• A. $3.14\times {10}^{2}weber/m^2$
• B. $6.28\times {10}^{-2}weber/m^2$
• C. $9.42\times {10}^{-2}weber/m^2$
• D. $12.56\times {10}^{-2}weber/m^2$

Answer 1

The correct option is B $6.28\times {10}^{-2}weber/m^2$

$B={\mu }_{0}ni=4\pi \times {10}^{-7}\times \frac{200}{{10}^{-2}}\times 2.5=6.28\times {10}^{-2}Wb/m^2$