It's in the negative direction since acceleration is in positive direction.
The magnetic field must first be in the opposite direction from acceleration, since acceleration occurs in the positive x-direction.
We know that the magnitude of the Lorentz force F is; F = q v B sinθ
So, B = F/(qvsinθ)
F = ma.
Speed(v) = 1.25 x10^(7) m/s
Acceleration (a) = 2.45 x10^(13) m/s^(2)
Mass of proton = 1.673 × 10^(-27) kilograms
q(elementary charge of proton) = 1.602×10^(−19)
Since right hand thumb rule, θ= 90°
So, B = [1.673 × 10^(-27) x 2.45 x10^(13)] / [ {1.602×10^(−19)} x {1.00 x10^(7)} x sin 90]
So ,B = 2.55 x 10^(-2) T.
It's in the negative direction since acceleration is in positive direction.
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