Question

Two coaxial solenoids are made by winding thin insulated wire over a pipe of cross sectional area $A=10c{m}^2$ and length $=20$ cm. If one of the solenoids has $300$ turns and the other $400$ turns, their mutual inductance is :

$({\mu }_0=4\pi \times {10}^{-7}Tm{A}^{-1})$

• A. $4.8\pi \times {10}^{-5}H$
• B. $2.4\pi \times {10}^{-4}H$
• C. $2.4\pi \times {10}^{-5}H$
• D. $4.8\pi \times {10}^{-7}H$

Answer 1

Answer: (B)

$2.4\pi \times {10}^{-4}H$

$M=\frac{{\mu }_0{N}_1{N}_{2}A}{l}=\frac{4\pi \times {10}^{-7}\times 300\times 400\times 10\times {10}^{-4}}{0.2}=2.4\pi \times {10}^{-4}H$