If you connect a DC shunt motor to an AC power source, what happens to the motor?

When a DC shunt motor is connected to an AC power source, the motor runs inefficiently due to the inherently different nature of the two types of electricity. DC motors are designed to operate with direct current, where the current flows in a constant direction, allowing the motor to create a magnetic field that rotates the rotor smoothly.

However, when connected to an AC source, the alternating current causes the direction of the current and the magnetic field within the motor to reverse periodically. This reversal disrupts the continuous rotation of the rotor, leading to inefficient operation. The motor may still run, but it will produce erratic torque and generate excessive heat due to the continuous changing of magnetic fields.

Running a DC motor on AC can also lead to mechanical stress and increased wear, potentially damaging the motor over time. In extreme cases, the excessive heating could result in more severe failures, but it's not guaranteed to explode. Thus, the primary consequence of connecting a DC shunt motor to AC power is its inefficient operation, which aligns with the correct answer.