Introduction:
In an electric circuit, current refers to the flow of electric charge. It is the movement of electrons through a conductor. The flow of electric current is influenced by various factors, including potential difference, temperature, and resistance. However, the primary factor that determines the flow of current is the potential difference.

Explanation:

Potential Difference:
- The potential difference, also known as voltage, is the driving force that pushes the electric charges to move in a circuit.
- It is the difference in electric potential energy per unit charge between two points in a circuit.
- When there is a potential difference across a conductor, the electrons experience an electric field that exerts a force on them, causing them to move.

Flow of Electric Current:
- Electric current flows from a region of higher potential to a region of lower potential.
- In a circuit, the potential difference is created by a power source such as a battery or a generator.
- The power source maintains a constant potential difference across the circuit, which causes the electrons to continuously flow and complete the circuit.

Importance of Potential Difference:
- Without a potential difference, there would be no force to move the electrons, and hence no current flow.
- The potential difference establishes an electric field, which allows the electrons to overcome the resistance offered by the conductor and flow through it.

Other Factors:
- Temperature does have an influence on the resistance of a conductor, which in turn affects the flow of current. However, it does not directly cause current flow.
- A difference in current can exist in a circuit, such as in series and parallel circuits, but it is not the primary factor that determines the flow of current.

Conclusion:
In summary, the flow of electric current in an electric circuit is primarily determined by the potential difference across the circuit. The potential difference creates an electric field, which provides the driving force for the movement of electrons. While other factors like temperature and resistance can affect the flow of current, they do not directly cause current flow.