Moderate

An electron enters a region where the electric field E is perpendicular to the magnetic field B. It will suffer no deflection if_________________?

Correct answer: C. E = BV

  • A. E = BeV
  • B. B = eE/V
  • C. E = BV
  • D. E = BeV/2

Explanation

For no deflection, the electric and magnetic forces must be equal: eE = evB, so E = vB. The likely wrong choice is b, B = eE/V, which incorrectly retains the charge e even though it cancels from both force expressions.

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About Charged Particle in a Magnetic Field

A charged particle moving through a magnetic field experiences the Lorentz force, which is perpendicular to both its velocity and the field. The motion may be circular or helical, with questions involving radius, angular frequency, time period, and work done. A stationary charge feels no magnetic force.

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