Understanding Velocity Selectors: The Intersection of Electric and Magnetic Fields
This text explores the concept of velocity selectors that combine electric and magnetic fields to selectively filter charged particles based on their velocities. When an electric field (E) and a magnetic field (B) are applied perpendicularly in the same region, forces act on charged particles. These forces can be balanced when a particle moves at a specific speed, allowing it to pass through without deflection. The principles governing this phenomenon can be expressed mathematically, underlining its significance in AP physics discussions.
Understanding Velocity Selectors: The Intersection of Electric and Magnetic Fields
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Presentation Transcript
Magnetism More on magnetism, including combining electric & magnetic fields to make a velocity selector
“Velocity selector” • If an Electric Field and Magnetic field are present in the same region, these can be used to “select” charges which are moving at a certain velocity. • Both the E field and B field create forces acting on a moving charge. • When the E field and B field are perpendicular to eachother and “tuned” correctly, the 2 Forces are balanced (this happens at a specific speed of the moving charge)
Velocity selector • Both magnetic and electric fields together
“Velocity Selector” • For the Electric Field: E = F/q or Fe=Eq • For the Magnetic Field: Fm=qvB • To determine the case where the charged particle cruises through without being deflected, set the 2 forces equal to eachother. • Eq = qvB, or v = E/B. • This “idea” has been on many AP free response questions.
