Lorentz Force on Charged Particles

Steps:

• Electrons, being negatively charged, experience a magnetic force F = q(v × B) when moving in a uniform magnetic field B.
• The force is always perpendicular to both velocity v and B, causing no change in speed but altering direction.
• If v is perpendicular to B, the path is circular with radius r = mv / |q|B.
• The direction follows the left-hand rule for negative charges, determining the curve.

Why D is correct:

• D depicts a circular path curving correctly per the Lorentz force law for electrons entering perpendicular to B.

Why the others are wrong:

• A shows straight line, incorrect as magnetic force deflects charged particles unless v parallel to B.
• B shows parabola, wrong as that's for uniform electric fields, not magnetic.
• C shows helix, incorrect without a velocity component parallel to B.

Final answer: D