Answer
(a) horizontal
(b) $29.3mV$
Work Step by Step
(a) As the coil rotates along the vertical axis, the vertical component of the magnetic field is always parallel to the coil's plane. Because of this, the vertical component doesn't contribute to the magnetic flux. Thus, only the horizontal component of the magnetic field is important.
(b) We can find the maximum induced emf as follows:
$\mathcal{E}_{max}=NBA\omega$
We plug in the known values to obtain:
$\mathcal{E}_{max}=\pi(155)(3.80\times 10^{-5})(0.11)^2(1250~rev/min)(2\pi~rad/rev)(1~min/60s)$
$\mathcal{E}_{max}=29.3mV$
