Answer:
B = 6.18 10⁻⁶ T
the magnetic field is in the negative direction of the y axis
Step-by-step explanation:
The magnetic force is given by
F = q v x B
as in the exercise indicate that the velocities perpendicular to the magnetic field,
F = q v B
Newton's second law is
F = m a
let's substitute
q v B = m a
B = m a / q v
let's calculate
B = 9.1 10⁻³¹ 2.50 10¹³ / (1.6 10⁻¹⁹ 2.30 10⁷)
B = 6.18 10⁻⁶ T
The direction of the field can be obtained with the right hand rule, where the thumb points in the direction of the velocity, the fingers extended in the direction of the magnetic field and the palm in the direction of the force for a positive charge.
In the exercise indicate that the velocity is the z axis
the acceleration and therefore the force in the x axis
therefore the magnetic field is in the negative direction of the y axis