91影视

The magnetic force and electrical force

\(qvB = qE + mg\)

The value of mass is,\(m = 4.25\,{\rm{g}}\)

The value of charge is,\(q = 2500\,{\rm{\mu C}}\).

The initial velocity is, v = 112.8m/s

The value of field strength is, E = 27.5N/C.

The magnetic force is given by

\(qvB = qE + mg\)

Therefore,

\(B = \frac{{qE + mg}}{{qv}}\)

Substitute all the value in the above equation.

\(\begin{aligned}{}B = \frac{{\left( {2500 \times {{10}^{ - 6}}\,{\rm{C}}} \right)(27.5\,{\rm{N/C}}) + (0.00425\,{\rm{kg}})\left( {9.80\,{\rm{m/}}{{\rm{s}}^{\rm{2}}}} \right)}}{{\left( {2500 \times {{10}^{ - 6}}\,{\rm{C}}} \right)(12.8\,{\rm{m/s}})}}\\ = 3.45\;\,{\rm{T}}\end{aligned}\)

Since the direction of the electric field is downwards, so the magnetic force is upwards.

Therefore, the direction of the magnetic field is into the page.

Therefore, the magnetic field is \(3.45\;\,{\rm{T}}\)