# Does potential drop when a charge flows through a wire w/ 0 resistance?

• Kaushik
In summary, connecting a battery with potential difference V to a wire with zero resistance causes the charges in the wire to move due to the electric field created by the battery. This results in a decrease in potential energy for the charges as they move from the positive to the negative terminal. If the wire has non-zero resistance, this potential energy is converted into thermal energy. However, if the wire has zero resistance, the potential energy is dissipated in the battery. The straight lines connecting resistors in a circuit diagram represent equipotentials or wires with zero resistance.

#### Kaushik

Let us connect a battery of potential difference V to a wire. There is no resistance. Nothing!

Now the battery creates some potential difference and the charges in the conducting wire move due to the Electric field created in the conductor by the battery. So, as the charge moves, its potential energy should decrease. Isn’t it?

This happens when a positive point charge is kept in space. When we move a unit positve charge towards it, the potential increases as we move towards that point charge.

I have the exact same question as the following:

https://physics.stackexchange.com/questions/262698/why-is-there-only-a-drop-in-potential-energy-when-charges-flow-through-a-resistor

Last edited:
Kaushik said:
Summary:: .

Now the battery creates some potential difference
You missed out a step here. The battery has an emf which is the potential across the terminals with no load. Once you connect the ideal wire, the current flows and the PD across the internal resistance develops.

• Kaushik
Suppose you have the terminals of a battery not connected to anything. There is an electric field between its terminals. Let's say that a positively-charged ion is near the positive terminal. It will accelerate in the electric field and in so doing it will lose potential energy and gain kinetic energy. This much should be obvious to you.

Now suppose you connect the terminals with a wire. The wire has some resistance. The job of the battery is to maintain a constant potential difference between its ends. The positive terminal is at a higher potential than the negative and there is an electric field inside the conducting wire pointing from plus to minus. Charge carriers (assumed positive by convention) will move from the positive terminal terminal to the negative which means they lose potential energy. However they do so without gaining kinetic energy because they move at constant speed. You can view the loss of potential energy as gain in thermal energy, i.e. heat dissipated in the resistor.

BTW, the link you provided does not work; you need to add a final "r" in "resisto" to make it work.

• Kaushik
kuruman said:
Suppose you have the terminals of a battery not connected to anything. There is an electric field between its terminals. Let's say that a positively-charged ion is near the positive terminal. It will accelerate in the electric field and in so doing it will lose potential energy and gain kinetic energy. This much should be obvious to you.

Now suppose you connect the terminals with a wire. The wire has some resistance. The job of the battery is to maintain a constant potential difference between its ends. The positive terminal is at a higher potential than the negative and there is an electric field inside the conducting wire pointing from plus to minus. Charge carriers (assumed positive by convention) will move from the positive terminal terminal to the negative which means they lose potential energy. However they do so without gaining kinetic energy because they move at constant speed. You can view the loss of potential energy as gain in thermal energy, i.e. heat dissipated in the resistor.

Now, what happens if we connect a battery to a wire with 0 resistance (which is not what happens in reality)?

In the case of wire with resistance, as you said, the thermal energy of the positive ions that constitue the resistor (here, a wire with some resistance) increases.

But what about a wire with 0 resistance? Is there a decrease in potential energy of the positive charge (by convention) as it moves from the positive terminal to the negative terminal (that is what I expect)? If yes, where does this loss in potential energy go so that the energy is conserved?

kuruman said:
BTW, the link you provided does not work; you need to add a final "r" in "resisto" to make it work.
Thanks! Fixed it What happens if you apply an irresistible force to an immovable object?

kuruman said:
lose potential energy and gain kinetic energy
The Kinetic Energy involved is near zero the speeds are extremely low . The electron drift speed is around 1mm/s. The Energy conversion takes place in the Load, either heating an element or moving with a motor. The OP starts off with no resistance in the wire, which is a fair start with a normal battery and a 15mm2 copper wire. The only resistance in the proposed setup is in the battery and it is usually treated as ohmic (an approximation).
Kaushik said:
If yes, where does this loss in potential energy go so that the energy is conserved?
It is dissipated in the battery, as above. Connect a fat piece of copper wire across a car battery and it can boil and explode.

• Kaushik
jbriggs444 said:
What happens if you apply an irresistible force to an immovable object?
You blow the side of the battery off - or melt the wire coat hanger.

Kaushik said:
Now, what happens if we connect a battery to a wire with 0 resistance (which is not what happens in reality)?
In reality you can connect the battery to a wire with zero resistance using leads with non-zero resistance. This is routinely done, for example, when people charge or discharge superconducting coil magnets.

Have you ever wondered what the straight lines connecting resistors in a circuit diagram represent? They should not be thought of as wires but as equipotentials or wires with zero resistance in which case Ohm's law ##V=IR## still applies. The fact that ##R=0## necessitates that ##V=0## but the current ##I## can be anything. Note: ##V## in this context is the potential difference between the ends of the straight line segment.

• etotheipi and Kaushik

## 1. What is potential drop in a wire?

Potential drop, also known as voltage drop, is the decrease in electric potential that occurs when an electric charge flows through a conductor, such as a wire.

## 2. How is potential drop related to resistance?

According to Ohm's Law, potential drop is directly proportional to resistance. This means that as resistance increases, potential drop also increases.

## 3. Does potential drop occur when there is no resistance in a wire?

No, potential drop only occurs when there is resistance in a wire. In a wire with 0 resistance, the potential drop is also 0.

## 4. Can potential drop be measured in a wire with 0 resistance?

No, potential drop cannot be measured in a wire with 0 resistance because there is no resistance for the charge to flow through and create a potential difference.

## 5. How does potential drop affect the flow of charge in a wire?

Potential drop is necessary for the flow of charge in a wire. It provides the driving force for the charge to move through the wire. Without potential drop, there would be no flow of charge.