Question

A flat circular coil of 1 cm radius is rotated at 10 revolutions per second about an axis that is perpendicular to a uniform magnetic field of magnitude 2.5 T. How many turns are required in the coil to generate a peak voltage of 750 mV?

- 2 turns

- 5 turns

- 8 turns

- 15 turns

- 20 turns

Answer 1

There is 10 revolution per secona. Answer Given, Radius of coil, s= 1 cm = '01m e area of the coil, A TO -3. 14x10 m A = 3.14 X0.01) m magnetic field, B= 2:55 &= 750 mv = 750x103 v peak voltage, & _'. angulart frequency W = 25 x 10 radys = 62.8 radis Let there is N no. of furn in the coil Now, if any time normal to the coil makes an angle o with magnetic field then magnetic flux, flux, p = = NB A COSO = NBA Coswt

dt 30, induced emf, &=-18 - 2 1 (NBA Coswt) - NBAW sinut When, &=&o (Peak voltage) then Sinut 1 - Peak voltage, Eo = NBAW =>N= Eo BAW 750X10 2.5 X 3.14x10 9X628 15.21 * 15
So there is 15 number of turns required to generate peak voltage 750mV