Question

The magnetic field due to a long straight wire has been derived in terms of µ, i and d. Express this in terms of ε₀, c, i and d. 

Answer 1

The magnetic field due to a long, straight wire is given by

\[B = \frac{\mu_o i}{2\pi d}\]
\[ \because \text{ Speed of light }, c = \frac{1}{\sqrt{\mu_o \epsilon_o}}\]
\[ \Rightarrow \mu_o = \frac{1}{c^2 \epsilon_o}\]
\[ \Rightarrow B = \frac{i}{2 \pi c^2 \epsilon_o d}\]

(In terms of ε₀, c, i and d)