Relativistic momentum through a magnetic field

[Physics reptile]

Homework Statement

A particle with large momentum (relativistic) p , goes through a region with magnetic field 4 tesla
perpendicular to p. The region is 15 cm in length. What is the deflection theta of the particle after it crosses the region.

Relevant Equations

Magnetic field eqation,small angle approximation

p=Bqr and del p = p del theta

 

[anuttarasammyak]

$$\theta=\frac{\triangle p}{p}$$
where $\triangle p$ is momentum gain from the magnetic field.
$$\triangle p=F \triangle t$$
where F is force applied to the particle and $\triangle t$ is time interval when the particle stays in the region.