Question

What is \[M_{21}\] for two coaxial solenoids with the smaller solenoid inside the larger?

Options

• \[M_{21}=\mu_0n_1n_2\pi r_1^2l\]

• \[M_{21}=\mu_0n_1n_2\pi r_2^2l\]

• \[M_{21}=\mu_0n_1n_2\pi r_2^2lI_1\]

• \[M_{21}=\frac{\mu_0n_1n_2\pi r_2^2}{l}\]

Answer 1

Divide the secondary’s total flux linkage by the primary current \[I_1\] . The resulting mutual inductance is \[M_{21}=\mu_0n_1n_2\pi r_2^2l\] .