The observations regarding the bulb connected to a bicycle dynamo—where it glows brightly, dims, and eventually turns off when the bicycle comes to rest—can be explained by the following points based on the working principle of a dynamo:

1. Dependence on Wheel Rotation: The dynamo generates electricity through electromagnetic induction, which occurs when a magnet rotates within a coil of wire.     The faster the wheel spins, the more electricity is produced. When the bicycle is in motion, the dynamo generates enough power to keep the bulb bright.                                                   However, as the speed decreases, less electricity is produced, causing the bulb to dim.
2. Loss of Power at Rest: When the bicycle comes to a complete stop, the dynamo ceases to generate electricity because there is no longer any rotation of the magnet within the coil. As a result, the bulb will turn off completely since it relies on the electrical energy generated by the dynamo.             

These factors illustrate how the performance of a dynamo is closely tied to the mechanical motion of the bicycle, affecting the brightness of the connected bulb.