An aircraft with a wingspan of 40 m flies with a speed of 1080 km h^–1 in the eastward direction at a constant altitude in the northern hemisphere, where the vertical component of earth's magnetic field is 1.75 x 10^–5 T. Then the e.m.f. that develops between the tips of the wings is

0.21V

$\xi = Blv $

$v = 1080km/h = 300m/s , B = 1.75 times 10^{-5} T , L = 40m$

$ \Rightarrow \xi = 0.21V$