An armature coil consists of 20 turns of wire, each of area $A=0.09 m^2$ and total resistance 15 Ω. It rotates in a magnetic field of 0.5 T perpendicular to the axis of rotation at a constant frequency $\frac{150}{π}$ Hz. The value of maximum emf produced in the coil is:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 270 V
The maximum emf ($ε_{max}$) induced in a rotating coil is given by the formula -
$ε_{max}=N.B.A.ω$
where,
N, Number of turns = 20
B, Magnetic field = 0.5 T
A, Area of each turn = $0.09m^2$
f, rotational frequency = $\frac{150}{π}Hz$
Angular frequency, $ω=2πf$
$=2π×\frac{150}{π}$
= 300 rad/s
$∴ ε_{max}=20×0.5×0.09×300$
$=270V$