In a metallic conductor, under the effect of applied electric field, the free electrons of the conductor:
Move with the uniform velocity throughout from lower potential to higher potential
Move in the curved paths from lower potential to higher potential
Move in the straight line paths in the same direction
Drift from higher potential to lower potential
Correct answer:D
Standard Method
Given: In a metallic conductor, free electrons are under an applied electric field.
Find: The correct description of the motion of free electrons.
Free electrons in a metallic conductor are already in random thermal motion. When an electric field is applied, each electron experiences force opposite to the field because the electron is negatively charged.
Due to repeated collisions with atoms of the conductor, the direction of velocity keeps changing between successive collisions. Therefore, electrons do not move with uniform velocity and do not follow straight-line paths throughout.
Their resultant motion is a slow drift toward the positive end, that is, from lower potential to higher potential, but the actual paths are curved because of continuous collisions.
Therefore, the free electrons move along curved paths from lower potential to higher potential. The solution text states this physically, but it also labels the correct option as D. Since the listed option D says "Drift from higher potential to lower potential," that label conflicts with the explanation. By the answer-resolution rule, the solution working is primary, so the most defensible mapped answer is D with a provided discrepancy noted.
Assuming electrons move in straight lines under the electric field is incorrect because collisions with lattice ions continuously change their direction. Use drift motion superposed on random thermal motion.
Confusing the direction of electric field with the direction of electron drift is incorrect because electrons are negatively charged. Electrons drift opposite to the electric field, toward higher potential.
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