One school child asked me -

If current means flow of electrons, or entering to a bulb from one wire (Live) then going back through another wire, then why there is no current in the neutral wire, because electrons or charges is still flowing through it as part of going back?

I could not answer him, so kindly advise, what exactly the neutral line is, what is happening in neutral wire , why it is important for , why it has no electricity? Kindly provide a simple answer (if possible some examples with water or other comparable things)

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    \$\begingroup\$ "there is no current in the neutral wire" where does this assumption come from? \$\endgroup\$ – dim lost faith in SE Apr 16 '19 at 9:13
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    \$\begingroup\$ Ahhh. Take a look at those wires. If there were no current flowing through the neutral, then you could use a much thinner wire for neutral. But, neutral is as thick as the live. Current does flow through the neutral. The voltage on the neutral is very close to zero as measured between neutral and the literal ground beneath your feet. That's because neutral is connected to the earth ground wire in your house, and earth ground is connected to the literal ground beneath your feet. \$\endgroup\$ – JRE Apr 16 '19 at 9:15
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    \$\begingroup\$ This is a misunderstanding of what current and voltage are. The child doesn't know - hasn't had a chance to learn it. If you are a science teacher, then you need to improve your own understanding of voltage and current. \$\endgroup\$ – JRE Apr 16 '19 at 9:18
  • \$\begingroup\$ Here is a good summary of electricity and home wiring. \$\endgroup\$ – JRE Apr 16 '19 at 9:45
  • \$\begingroup\$ We had a good demonstration in class - Van der Graff generator with all the class on rubber mats & holding hands except for the one at the end who stood on the floor... Then the teacher touched the generator - no one noticed except the kid at the end :) I suppose this would be a banned activity by the H&S police now... \$\endgroup\$ – Solar Mike Apr 16 '19 at 9:52

... then why there is no current in the neutral wire?

Yes, Virginia, there is a current.1.


simulate this circuit – Schematic created using CircuitLab

Figure 1. The building supply comes from the utility company's transformer. One of the transformer outputs is connected to earth and so is "neutralized.

Current must return to the source as you suspect. The pupil may be getting confused with voltage and since the neutral wire is connected to earth there is, nominally, no voltage on the neutral wire with respect to earth. In practice the neutral wire has some resistance so a voltage proportional to the current (V = IR, Ohm's Law) will appear at the lower terminal of the lamp. This shouldn't be more than a couple of volts in normal operation.

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