What is the reason for the infinite voltage and zero current in an open circuit?

From the nature of voltage understanding open circuit voltage infinity (ideal)

Voltage definition

Voltage is the work done by an electric field force to move a unit of positive charge from one point to another, i.e

U=W/q

There's voltage, there's work, there's charge. In the open state, there is no current path, we can consider from the point of view of the electric field.

Electric field conditions at open circuit

When the circuit is open, it is assumed that there is an electric field between the two poles of the power supply, such as the positive and negative poles of the battery. Since there is no current, charges cannot flow through the circuit to balance this electric field. Theoretically, if we move a charge q from the negative electrode of the power supply to the positive electrode (along the direction of the electric field line), because there is no current path, the charge will not have other energy losses in the process (such as heat loss due to resistance in the conductor, etc.), so it is necessary to do infinite work to overcome the electric field force, according to the definition of voltage, at this time the voltage approaches infinity. But this is an ideal, theoretical situation, in practice there is no absolute open circuit without leakage.

The cause of zero current in open circuit

Conditions for current formation

Current is formed by the directional movement of electric charges. In a circuit, to have a continuous current, two conditions must be met: first, there is a charge that can move freely (such as free electrons in a metal conductor); The second is that there is an electric field that causes the charge to move in a directional manner, and the circuit must be closed.

The state of the circuit when it is open

In the open state, the circuit is not a closed loop. For example, when a wire is disconnected in the middle, although there are free electrons (charges that can move freely) in the wire, and there is an electric field at both ends of the power supply, because the circuit is disconnected, the electrons cannot form a directional movement at the disconnect, so the current is zero.