# Why is there EMF present when there is no current?

Current means the rate of flow of charge. Electrons are the ones that carry charge in current. From the definition of EMF (electromotive force),

When no current is drawn from cell, the potential difference between terminals of cell is called: EMF of cell.

EMF is potential difference of the cell. Now, potential difference is the work done by carrying a unit charge from one point to another. Therefore, if there is no current, nothing is carrying any charge. Therefore, 0 EMF as well?

• So, does an object held at a height have zero gravitational potential energy just because it isn't in motion? No, because that's kinetic energy. You're having a similar confusion between the two. Commented Nov 18, 2021 at 5:44
• "Potential" means "not yet realized". 1V of potential means that if 1 amp were to flow you would get 1 watt. It doesn't mean you are currently getting any power. See also, potential energy for a related concept. Also, there are currents where positive charge carriers flow instead of electrons, so it's not good to think of current as being exclusive to electrons. Commented Nov 18, 2021 at 6:19
• Water analogy; if you have a garden hose, there's pressurized water in the hose, so it is ready to flow out when you open the valve. That's why a 9V battery has 9V on the terminals even if you draw no current. Commented Nov 18, 2021 at 7:24
• @Justme Do you mean to say that there is current present In the wires & cell but just not flowing. Commented Nov 18, 2021 at 8:20
• "Electrons are the ones that carry charge in current." Try to avoid thinking that way. Current can be transferred by ions as well. It's electrons in metallic conductors but for most circuit analysis thinking in terms of electrons isn't useful. Commented Nov 18, 2021 at 12:29

Current is the flow of charge. Voltage is the potential energy per unit charge.

The charge is in the cell, but it is not flowing. The EMF's potential voltage is there, just waiting to be used.

Emf or voltage is defined as potential energy per unit charge or per 1 coulomb of charge. Even if there is no current potential per unit charge is still there. As soon as the path is found that potential will cause current.

If you are holding a stone in your hand it has the potential to moves towards the earth. As soon as you release the stone it starts moving.

From the definition of EMF (electromotive force),

When no current is drawn from cell, the potential difference between terminals of cell is called: EMF of cell.

You've quoted this 'definition' from a picture you quoted in a chatroom:

That statement -When no current is drawn from cell, the potential difference between terminals of cell is called: EMF of cell.- isn't a definition of EMF. It's a statement of what the potential difference (pd or what we commonly call voltage) is between the terminals of the cell when there is no load current. When there's no load on the cell the pd at the terminals = the EMF of the cell.

Wikipedia gives a short definition of EMF as "the electrical action produced by a non-electrical source." I'd prefer to change 'the electrical action' to 'a source of voltage'. The non-electrical source could be chemical, such as your galvanic cell, caused by a varying magnetic field e.g in a inductor, transformer, motor or generator or a receiving radio aerial, or a solar cell, powered by light. The Wikipedia article discusses these sources in more detail.

Note the 'non-electrical source'. We don't usually say a power supply circuit provides an EMF because it's getting its power from an electrical source.