Question

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

• A. $314x{10}^{-2}Wb/m^2$
• B. $6.28x{10}^{-2}Wb/m^2$
• C. $9.42x{10}^{-2}Wb/m^2$
• D. $12.56x{10}^{-2}Wb/m^2$

Answer 1

The correct option is B $6.28x{10}^{-2}Wb/m^2$

The magnetic field at the centre is given as,

$B={\mu }_{0}IN$

$=4\pi \times {10}^{-7}\times 2.5\times 20000$

$=6.28\times {10}^{-2}Wb/m^2$

Thus, the magnetic field at the centre is $6.28\times {10}^{-2}Wb/m^2$.