A charged particle is introduced at the origin x=0, y=0, z=0 with a given initial...
A charged particle is introduced at the origin x=0, y=0, z=0x=0, y=0, z=0 with a given initial velocity →v→v . A uniform electric field →E →E and a uniform magnetic field →B→B exist everywhere. The velocity →v→v , electric field →E →E and a uniform magnetic field →B→B are given in the columns below
In which case will the particle describe a helical path with axis along positive z direction?
Column 1 | Column 2 | Column 3 |
1. Electron with →v=2E0B0ˆx →v=2E0B0ˆx | (i) →E=E0ˆz→E=E0ˆz | (P) →B=-B0ˆx →B=−B0ˆx |
2. Electron with →v=2E0B0ˆy →v=2E0B0ˆy | (ii) →E=-E0ˆy →E=−E0ˆy | (Q) →B=B0ˆx →B=B0ˆx |
3.Proton with →v→v =0 | (iii) →E=-E0ˆx →E=−E0ˆx | (R) →B=-B0ˆy →B=−B0ˆy |
4. Proton with →v=2E0B0ˆx →v=2E0B0ˆx | (iv) →E=E0ˆx →E=E0ˆx | (S) →B=-B0ˆz →B=−B0ˆz |
Solution:
For path to be helix with axis along +ve z-direction, particle should experience a centripetal acceleration in x-y plane.
For the given set of options only option (4) (i) (S)(4) (i) (S) satisfy the condition. Path is helical with increasing pitch.
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