An AC generator converts mechanical energy into electrical energy using electromagnetic induction. It consists of a coil rotating in a magnetic field, with slip rings and brushes to transfer the induced current to an external circuit. As the coil rotates, the magnetic flux through it changes, inducing an alternating voltage. This creates a sinusoidal potential difference between points X and Y in the circuit, as shown in the graph. Point P marks a specific position on this waveform, which corresponds to a particular orientation of the coil.
The graph shows how the potential difference between points X and Y varies over time as the coil rotates. When the p.d. is positive, point X is more positive than Y. When negative, Y is more positive than X. The p.d. reaches its maximum value when the coil is horizontal, and zero when the coil is vertical. Point P on the graph marks the first negative peak, where the p.d. is at its maximum negative value. This corresponds to a specific position of the coil in the magnetic field. At this position, the coil is horizontal, but with the opposite orientation compared to the positive peak.
Let's analyze the coil position at point P, which is the first negative peak on the graph. At this position, the coil is horizontal and parallel to the magnetic field. The potential difference between X and Y is at its maximum negative value, meaning Y is more positive than X. This causes current to flow from Y to X in the external circuit. Using Fleming's Right-Hand Rule, we can determine that the current in the coil flows upward on the side near the North pole and downward on the side near the South pole. This specific configuration of the coil position and current direction corresponds to option A in the multiple-choice question.
Let's compare all four options to determine which one correctly shows the coil position at point P. Option A shows the coil in a horizontal position with current flowing upward near the North pole and downward near the South pole. This matches our analysis for point P. Option B shows the coil in a vertical position, but at point P, the coil must be horizontal since it's at a peak of the waveform. Option C also shows a vertical coil, which is incorrect for the same reason. Option D shows a horizontal coil, but the current direction is opposite to what we determined using Fleming's Right-Hand Rule. Therefore, option A is the correct answer.
To summarize what we've learned: AC generators convert mechanical energy to electrical energy through electromagnetic induction. As the coil rotates in the magnetic field, the potential difference between points X and Y varies sinusoidally. At point P, which is the first negative peak on the graph, the coil is in a horizontal position with current flowing upward on the side near the North pole and downward on the side near the South pole. We can use Fleming's Right-Hand Rule to determine the direction of induced current in the coil based on the magnetic field direction and the motion of the coil. By analyzing the coil position and current direction, we determined that option A correctly shows the configuration at point P.