Concepts Of Physics MCQ Edition [Volume 2]PhysicsMagnetic Field
A narrow beam of protons having kinetic energy K emerges from an accelerator. The beam is deflected by a perpendicular magnetic field such that it just misses a plane target kept at a distance l in front of the accelerator. Determine the magnetic field. (Assume m_p and e represent the mass and charge of a proton, respectively).
Options
- Am_p K e l
- B2 2 m_p K e l
- C2 m_p K 2 e l
- D2 m_p K e l
Correct answer
D. 2 m_p K e l
Step-by-step solution
The momentum of a proton with kinetic energy K is given by p = 2 m_p K . When the proton beam enters a perpendicular magnetic field B , it follows a circular path of radius R given by: R = p eB = 2 m_p K eB The protons emerge from the accelerator and move towards the plane target. The maximum forward distance traveled by a particle moving in a circular path (starting from the origin and tangent to the initial velocity) is equal to its radius R . For the beam to just miss the plane target kept at a distance l in fro