AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.
The force on a current-carrying conductor is largest when the direction of current is perpendicular (at right angles) to the direction of the magnetic field.
The textbook explicitly states: "the displacement of the rod is largest when the direction of current is at right angles to the direction of the magnetic field." Examiners expect the key phrase "at right angles" or "perpendicular" — either wording earns full marks. No additional explanation is needed for a 1-mark answer.
Source: Chapter 12, Section 12.3 – Force on a Current-Carrying Conductor in a Magnetic Field