Which of the following statements correctly describes the left-hand rule for determining magnet polarity?

• A. It uses the right-hand rule and the thumb points to the north pole.
• B. It uses the left-hand rule and the fingers curl in the direction of current.
• C. It uses the left-hand rule and the thumb points south.
• D. It uses the left-hand rule and the fingers encircle the coil in the direction electrons flow; the thumb points to the north pole.

Answer: (D)

Fleming’s left-hand rule is used to relate the direction of current in a coil to the magnetic polarity it produces. When you apply this rule to a coil, you orient your left hand so that your fingers curl in the direction that the electrons move around the windings. In that setup, your thumb points toward the end of the coil that becomes the north pole of the magnetic field. That alignment — left-hand, curling in the direction of electron flow, with the thumb indicating the north pole — is why this description correctly describes magnet polarity. The other formulations either switch to the right-hand rule or mix up the current direction (using conventional current instead of electron flow or claiming the thumb points to the south), which would not match the described rule.