Question

An upward force act on a proton as it moves with a speed of 2.0 x 10^5 meters/seconds through a magnetic field of 8.5 x 10^2

Answer 1

Force on a moving charge is given by formula

$\vec F = q(\vec v \times \vec B)$

here we know that this force will be maximum when velocity is perpendicular to magnetic field

$\vec F = qvB$

here we know that

$v = 2.0 \times 10^5 m/s$

$q = 1.6 \times 10^{-19} C$

$B = 8.5 \times 10^2 T$

now we have

$F = (1.6 \times 10^{-19})(2 \times 10^5)(8.5 \times 10^2)$

$F = 2.72 \times 10^{-11} N$