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प्रश्न
A cubical region of space is filled with some uniform electric and magnetic fields. An electron enters the cube across one of its faces with velocity v and a positron enters via opposite face with velocity – v. At this instant ______.
- the electric forces on both the particles cause identical accelerations.
- the magnetic forces on both the particles cause equal accelerations.
- both particles gain or loose energy at the same rate.
- the motion of the centre of mass (CM) is determined by B alone.
पर्याय
a, b and c
a, c and d
b, c and d
c and d
उत्तर
b, c and d
Explanation:
This problem is based upon the single moving charge placed with some uniform electric and magnetic fields in space. Then they experience a force called Lorentz force given by the relation Fnet = qE + q(v × B).
- The magnetic forces (Fm = q(v × B)), on charge particle is either zero or Fm is perpendicular to v (or component of v) which in turn revolves particles on a circular path with uniform speed. In both cases, particles have equal accelerations.
- Due to the same electric force (Fe = qE) which is in opposite direction (because of the sign of charge) both the particles gain or loss energy at the same rate.
- There is no change of the Centre of Mass (CM) of the particles, therefore the motion of the Centre of Mass (CM) is determined by B alone.
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