Answer
$B = 2.9~T$
Work Step by Step
$F = \frac{mv^2}{r}$
$F = qvB$
We can equate the two expressions for $F$ to find the value for $B$:
$\frac{mv^2}{r} = qvB$
$B = \frac{mv}{qr}$
$B = \frac{(4.003)(1.67\times 10^{-27}~kg)(0.458)(3.0\times 10^8~m/s)}{(2)(1.6\times 10^{-19}~C)(1.00~m)}$
$B = 2.9~T$
