A conducting circular loop is placed in a uniform magnetic field B = 0.25 T, with its plane perpendicular to the field. The radius of the loop is made to shrink at a constant rate of 1 mm/s. The induced emf, when the radius is 2 cm, would be
(1) \((\frac{\pi}{2})μV\)
(2) \((\pi)μV\)
(3) \((2\pi)μV\)
(4) \((2.5)\pi μV\)
