Question 5.2: A circular iron ring of mean diameter 25 cm and cross-sectio......

Basic Electrical and Electronics Engineering
Basic Electrical and Electronics Engineering [1015987]

A circular iron ring of mean diameter 25 cm and cross-sectional area 9 cm² is wound with a coil of 100 turns and carries a current of 1.5 A. The relative permeability of iron is 2000. Calculate the amount of flux produced in the ring.

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Mean length of flux path, $\ell=\pi \mathrm{D}=3.14 \times 25 \mathrm{~cm}=\frac{3.14 \times 25}{100} \mathrm{~m}=0.785 \mathrm{~m}$

Flux, $\phi=\frac{\mathrm{MMF}}{\text { Reluctance }}=\frac{\mathrm{NI}}{\ell / \mu_0 \mu_{\mathrm{r}} \mathrm{A}}=\frac{100 \times 1.5}{0.785 / 4 \pi \times 10^{-7} \times 2000 \times 9 \times 10^{-4}}$ .

\begin{aligned} & =\frac{150}{348 \times 10^3}=\frac{150}{348} \times 10^{-3} \\ & =0.431 \times 10^{-3} \mathrm{~Wb} \\ & =0.431 \mathrm{mWb} \end{aligned}

figure 5.21

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