An alpha particle (helium nucleus) travelling through interstellar space enters two adjacent regions containing different, uniform magnetic fields, as shown in the diagram.
The alpha particle enters Region X with an initial speed of 3.6 × 105 m s-1 and is deflected into a circular path of radius R1=12 kmR_1 = 12\text{ km}R1=12 km. Upon entering Region Y, its path has a radius of curvature of R2=4.0 kmR_2 = 4.0\text{ km}R2=4.0 km.
State the speed of the alpha particle as it exits Region Y, and explain why the magnetic fields in Region X and Region Y do not change its speed.