Question

A circular coil of radius 5 cm has 500 turns of a wire. The approximate value of the coefficient of self induction of the coil will be

• A. 25 millihenry
• B. 25 × 10^–3millihenry
• C. 50 × 10^–34millihenry
• D. 50 × 10^–3henry

Answer 1

Answer: (A)

25 millihenry

Answer 2

By using $L = \frac{\pi\mu_{0}N^{2}r}{2}$;

$L = \frac{(3.14) \times 4 \times (3.14) \times 10^{- 7} \times (500)^{2} \times 5 \times 10^{- 2}}{2} \approx 25 \times 10^{- 3}H \approx 25mH$