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⚛️ NEET Physics❓ Question

Charge is quantised as q = ne, but quarks have e/3. Does that break the rule? Also does a charged body gain mass?

Tanvi Deshmukh12th Sample

24 Aug 2026 · 1 min read

Making notes for Electric Charges and Fields (tables everywhere obviously!!) and the first page already has me confused.

NCERT lists the properties: additivity, conservation, quantisation. Quantisation says q=±neq = \pm ne with e=1.6×10−19e = 1.6\times10^{-19} C. But the same chapter mentions that protons and neutrons are made of quarks that carry charges ±13e\pm\frac{1}{3}e and ±23e\pm\frac{2}{3}e. So can the charge on a body be e/3e/3 or not??

And second thing. When I rub a glass rod with silk the rod becomes positive. Does the glass rod lose mass and the silk gain mass? Since electrons have mass, the total mass of rod+silk should not change, but each individually should. Is this too tiny to matter or is the idea itself wrong?

Also my teacher said "charge is conserved, but it can be created in pairs". That sounds contradictory!! Please explain like I am five 🙏

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  • [+]Arjun Nair12thSample· 1mo ago

    Quarks are never found alone. They are always confined inside particles like protons and neutrons, where the total charge works out to a whole multiple of ee. For example proton = up, up, down: 23+23−13=+1\frac{2}{3}+\frac{2}{3}-\frac{1}{3}=+1 in units of ee. Neutron = up, down, down: 23−13−13=0\frac{2}{3}-\frac{1}{3}-\frac{1}{3}=0.

    So for anything you can isolate, like a body or a free particle, the charge is an integer multiple of ee. NCERT even says the quantisation law stays valid for free charges.

  • [+]Harsh Gupta12thSample· 1mo ago

    Mass part: yes the glass loses some, the silk gains some, but it's so small you'd need a very very fancy balance. One coulomb is about 6.25×10186.25\times10^{18} electrons. Multiply by 9.1×10−319.1\times10^{-31} kg and you get around 5.7×10−125.7\times10^{-12} kg for an entire coulomb. And rubbing gives you microcoulombs at best. So the change in mass is "my weight after drinking a sip of water" level of invisible.

  • [+]Dev Agarwal12thSample· 1mo ago

    Quantisation only matters for really tiny charges, in everyday things we can't see it. That's why in a numerical the charge can be 1.5 μC, which is not a multiple of ee, so quantisation does not apply to macroscopic bodies.

    • [+]Neel Chatterjee12thSample· 1mo ago

      That's not right, Dev. 1.5 μC is 1.5×10−61.5\times10^{-6} C, which is about 9.4×10129.4\times10^{12} electrons' worth. It is a whole number multiple of ee (roughly). The law applies at all scales. It's just that ee is so small that a body having 101310^{13} electrons extra looks like a smooth continuous charge to us, like how a sand pile looks like a smooth slope from far away.

      • [+]Dev Agarwal12thSample· 1mo ago

        Ahh ok, so quantisation is always true, we just can't notice the steps. Makes sense, thanks Neel.

  • [+]Vivek Mishra12thSample· 1mo ago

    About "conserved but created in pairs". Conservation means the algebraic sum of charges in an isolated system stays the same. When a gamma ray makes an electron-positron pair, you start with total charge 0 and end with −e+(+e)=0-e + (+e) = 0. Created in pairs of opposite charge means the total does not change.

    NCERT example is similar: a neutral atom ionises into an electron and a positive ion, total still zero. You never get a single electron out of nothing.

    • [+]Tanvi Deshmukh12thSample· 1mo agoAuthor

      Okay!! Total charge zero before, zero after. I'm adding a box in my notes called "conservation = sum, not count". Thanks everyone!!!

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