After a dual-voltage motor is reconnected from a low-voltage circuit to a high-voltage circuit, the line current:

When a dual-voltage motor is reconnected from a low-voltage circuit to a high-voltage circuit, the line current is indeed lower. This phenomenon can be explained through the relationship between voltage, current, and power in electrical circuits.

In general, for a given power output (which the motor's load will demand), when the voltage is increased, the current drawn decreases, assuming efficiency remains relatively constant. The basic formula governing this relationship is derived from the power equation:

Power (P) = Voltage (V) × Current (I)

When you switch to a higher voltage while maintaining the same power output, the required current decreases as a result. For example, if a motor is capable of consuming a certain amount of power at a low voltage, when reconfigured to a high voltage, the reduced current allows for a more efficient operation and reduced losses due to resistance in the conductors.

This is why the current drawn from the power source is lower when the motor operates at a higher voltage, resulting in less energy wasted as heat, which ultimately makes the system more efficient. The correct choice reflects this understanding of electrical principles governing dual-voltage motors.