Q51 / 54 · JEE Advanced 2017 (Paper 1) · Physics

A charged particle is introduced at the origin x=0, y=0, z=0 with a given initial velocity v→ . A uniform electric field E→  and a uniform magnetic field B→ exist everywhere. The velocity v→ , electric field E→  and a uniform magnetic field B→ are given in the columns below
Column 1 Column 2 Column 3
1. Electron with  v→=2E0B0x^  (i) E→=E0z^ (P)  B→=-B0x^
2. Electron with  v→=2E0B0y^ (ii)  E→=-E0y^ (Q)  B→=B0x^
3.Proton with v→ =0 (iii)  E→=-E0x^ (R)  B→=-B0y^
4. Proton with  v→=2E0B0x^ (iv)  E→=E0x^ (S)  B→=-B0z^
In which case would the particle move in a straight line along the negative direction of y axis

  • A
    (4)  (ii)  (S)
  • B
    (3)  (ii)  (P)
  • C
    (2)  (iii)  (Q)
  • Correct answer
    D
    (3)  (ii)  (R)

Solution

For particle to move in -ve y-direction, either its velocity must be in –ve y-direction (if initial velocity ≠ 0) and force should be parallel to velocity or it must experience a net force in –ve y-direction only (if initial velocity = 0)

Hence, the correct answer is option: 'D'.

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