In the open circuit the current can not flow from one end of the power source to the other. Because of this there is no current flow, and therefore the light does not turn on.

Current flow basically means the flow of electric charges with respect to time. In an electric circuit, when the electric charge is flowing in one direction, the current will flow in the opposite direction. From Ohm’s law, the current can be defined as the voltage through the circuit per unit resistance.

There are two kinds of current electricity: direct current (DC) and alternating current (AC). With direct current, electrons move in one direction. Batteries produce direct current. In alternating current, electrons flow in both directions.

3 Answers. A current source can certainly have a voltage across it. If the voltage across a current source is zero, then it is not delivering or absorbing any power. However, if the voltage across the source is not zero, then it is either sourcing or sinking power into the rest of the circuit.

An ideal current source is a current source that supplies constant current to a circuit despite any other conditions present in the circuit. An ideal current source provides this constant current with 100% efficiency.

Comparison between voltage and current sources A real-world voltage source has a very low, but non-zero internal resistance and output impedance, often much less than 1 ohm. Conversely, a current source provides a constant current, as long as the load connected to the source terminals has sufficiently low impedance.

The force motivating charge carriers to “flow” in a circuit is called voltage. Voltage is a specific measure of potential energy that is always relative between two points. The amount of current in a circuit depends on the amount of voltage and the amount of resistance in the circuit to oppose current flow.

A constant voltage source is a power generator whose internal resistance is very low compared with the load resistance it is giving power to. Because its internal resistance is so low, it dumps most of its voltage across the higher resistance load.

The common constant voltage sources are the batteries and regulated power supplies. However, batteries cannot supply the constant voltage for a long time and must be recharged or replaced once exhausted. Further, a circuit may require other voltage levels different from what the batteries provide.

When the reverse voltage across a zener diode exceeds the breakdown voltage the current increases very sharply. In this region, the curve is almost vertical. It means voltage across zener diode is constant at even though the current through it changes. Therefore, a zener diode behaves as a constant voltage source.

Also for solving circuit analysis and complex theorems, voltage sources become short-circuited sources making their voltage equal to zero to help solve the network. Note also that voltage sources are capable of both delivering or absorbing power.