Question

An ac generator consists of a coil of 200 turns each of area 80$cm^{2}$and rotating at an angular speed of 200 rpm in a uniform magnetic field of 4.8×$10^{- 2}T.$ The rms values of emf induced in the coil is

• A. 22.68 V
• B. 11.37 V
• C. 7.39 V
• D. 18.67 V

Answer 1

Answer: (B)

11.37 V

Answer 2

: Here, N = 2000, A = 80 $cm^{2}$c

$B = 4.8 \times 10^{- 2}T,\upsilon = 200rpm = \frac{200}{60}rps$

$\omega = 2\pi\upsilon = \frac{2\pi \times 200}{60}\frac{20\pi}{3}rads^{- 1}$

$V_{0} = NBA\omega = 2000 \times 4.8 \times 10^{- 2} \times 80 \times 10^{- 4} \times \frac{20\pi}{3}$

$= 16.07V$

$\therefore V_{rms} = 0.707V_{0} = 0.707 \times 16.07$

$= 11.366V \approx 11.37V.$