Question

A rectangular coil 3x3 cm consisting of 100 turns caries 0.1 A. If it produces a deflection ${10}^0$, in a field of induction 0.1T, the couple per unit twist is

• A. $9\times {10}^{-2}Nm/Degree$
• B. $9\times {10}^{-5}Nm/Degree$
• C. $9\times {10}^{-2}Nm/rad$
• D. 0.9 Nm/Degree

Answer 1

Answer: (B)

$9\times {10}^{-5}Nm/Degree$

let C is the couple per unit twist.

$C\theta =NBAI$

$C=\left(\frac{NBI}{\theta }\right)$

=$\frac{100\times 0.1\times 3\times 3\times {10}^{-4}\times 0.1}{10}$

$C=9\times {10}^{-5}\frac{Nm}{Degree}$