When a wire is moved inside uniform magnetic field then its free electrons will experience magnetic force on it due to which wire will have potential difference at its ends.
Now here we will have magnetic field due to earth and wire is moving in this constant field so induced emf is given by formula

given that



now by using the above formula we will have



If you look below, we are using the centripetal acceleration formula. You just need to plug your numbers in and it should work!
Answer:
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Voltage = current * resistance
V = I*R
I = 4 A
R = 2 ohm
V = 4 A * 2 ohm
= 8 volt