When wings are along east-west, they intercept H.
`:. E = B l upsilon = H l upsilon`
`= (0.4 xx 10^(-4)) xx 30 xx (3 xx 10^(5))/(60 xx 60) = 0.1 V`
However, when wings are along north-south, H.
Intercept neither H nor V.So, in that case, induced e.m.f. = 0