Answer:
Step-by-step explanation:
Yes, the settings related to electric and magnetic fields need to be changed to select positrons with the same speed as electrons in a velocity selector.
A velocity selector is a device that selects charged particles of a specific speed. It consists of perpendicular electric and magnetic fields. The electric field accelerates charged particles, while the magnetic field deflects the particles in a circular path.
To select positrons with the same speed as electrons in a velocity selector, the direction of the magnetic field needs to be reversed, as positrons have the opposite charge to electrons and will therefore be deflected in the opposite direction.
The diagram below shows the setup of a velocity selector for electrons and how it needs to be modified to select positrons with the same speed:
Velocity Selector Diagram
In the original setup for electrons, the magnetic field is directed into the page, while the electric field is directed upwards. Electrons of a specific speed will travel in a circular path and exit the selector through a slit at the top.
To select positrons with the same speed, the direction of the magnetic field needs to be reversed, so that it is directed out of the page. This will cause the positrons to travel in a circular path in the opposite direction to electrons, and they will also exit through the slit at the top. The electric field can remain in the same direction, as it only serves to accelerate the charged particles.