Final answer:
A glass rod rubbed with silk itself does not produce a magnetic field, but when moving, it can slightly interact with Earth's magnetic field. An electric current in a solenoid, however, definitely produces a strong and uniform magnetic field, and is used in many practical applications.
Step-by-step explanation:
Objects that can produce magnetic fields include a variety of structures where electric currents are present. A glass rod rubbed with silk and observed in motion does generate a static charge but does not produce a magnetic field on its own. However, when it is moving, as in the case of a glass rod placed on a truck and observed from the ground, it could be considered a moving charge, which ultimately might yield a very small magnetic field due to its motion through Earth's magnetic field.
On the other hand, an electric current in a solenoid definitely creates a magnetic field. A solenoid is a coil of wire that when carrying an electric current, produces a magnetic field inside the coil. This field is quite uniform especially near the center of the coil, and its strength is directly proportional to the current flowing through the wire. Solenoids are utilized in numerous applications, such as electromagnets in machinery and medical devices like MRI machines. They are integral in the operation of many types of electric motors and generators.