ETO ETO Exam papers 📅 Mar 2022

Exam Question

(a) Explain the construction and principle of operation of permanent magnet moving coil instrument (8)

(b) A permanent magnet moving coil instrument has a coil of dimension 15mm X 12mm. The flux density in the air gap is 1.8 X 10^-3 wb/m2 and the spring constant is 0.4 X 10^-6 Nm /rad. Determine the number of turns required to produce an angular deflection of 90deg when a current of 5 mA is flowing through the coil (8)

Reference Answer

(a) answer will be here soon
(b) Given
Area $A = 15 \times 12 mm ^2 = 180 \times 10^{-6} m^2$
Flux density $B = 1.8 \times 10^{-3} {^{wb}/ {m^2}}$

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