# A jet plane is travelling towards west at a speed of $1800\; km/hr$. What is the voltage difference developed between the ends of the wing having a span of 25m, if the earth's magnetic field at the location has a magnitude of $5 \times 10^{-4} T$ and the dip angle is $30^{\circ}$
$(A) 31V$
$(B) 0.31V$
$(C) 310 V$
$(D) 3.1 V$