Understanding Circuit Resistance: Debunking the Myth of Zero Ohms

[forte74]

if i just measure the resistance btw L and N , the resistance should be zero right, then how can it be 0.3 ohms ?

 

[berkeman]

if i just measure the resistance btw L and N , the resistance should be zero right, then how can it be 0.3 ohms ?

What information are you given about the source impedance for the AC Mains feed of Line and Neutral into this circuit? The source impedance is in parallel with the circuit impedance.

Is this for schoolwork? If so, I will move your posts to the Homework Help forums.

 

[forte74]

im using the software for Troubleshooting Electrical circuits by BNN. studying this to get prepared as electrician. for if you look at the last 2 pictures, you can see that you can still get 0.3 ohms if the black wire is unplugged

 

[mr_pavlo]

I guess by zero resistance you mean infinite resistance. And does the circuit work as it should (all switches on - bulb shines, at least one off - bulb off). I hope, you measure it when you have the circuit disconnected from power source. And by the way, you measure on real circuit or are we still talking about that SW?

 

[alphy]

While it may seem intuitive that the resistance between the live (L) and neutral (N) wires in a circuit should be zero, this is not always the case. Resistance is a measure of how much a material or component impedes the flow of electric current. In an ideal conductor, such as a copper wire, the resistance would be zero. However, in real-world circuits, there are factors that can contribute to resistance, such as the material used, the length and thickness of the wire, and the presence of other components.

In the case of measuring the resistance between L and N, there are a few potential explanations for why it may not be zero. One possibility is that there is a small amount of resistance in the wires themselves, which is often the case in household wiring. Another factor could be the presence of other components, such as switches or outlets, which can also contribute to resistance.

It is also important to note that resistance is not a constant value, but can vary depending on the conditions in the circuit. For example, if the circuit is overloaded or there is a decrease in voltage, the resistance may increase.

In conclusion, while it may seem counterintuitive, it is possible for there to be a small amount of resistance between L and N in a circuit. This does not necessarily mean that the circuit is faulty, but rather that resistance is a natural and expected aspect of electrical circuits that must be taken into account when designing and measuring them.