What are the dimensions of `mu_0//4pi`?

What are dimensions of mu_0

What are the dimensions of K = 1//4 piepsilon_0 ?

The refractive index mu of a medium is found to vary with wavelength lambda as mu = A +(B)/(lambda^2). What are the dimensions of A and B?

The dimensions of mu_(0) are

The dimensions of mu_(0) are