Physics Van 3-site Navigational Menu

Physics Van Navigational Menu

Q & A: Do neutrinos have electric charge?

Learn more physics!

Most recent answer: 10/13/2015
Q:
I'e been reading that a neutrino nhas no electirc charge. But what about an electron neutrino (one of the three flavours)? Wouldn't this have a negative charge?
- Marc Inberg
Sydney Australia
A:
No, all three flavors of neutrinos have zero charge. For example a neutron can decay into a proton, an electron, and an electron anti-neutrino. Since charge is conserved and the fact that the charge on the electron is exactly equal and opposite to that of the proton,  that means there is nothing left over for the neutrino.     The neutrinos have slightly different interaction properties that distinguish them but electric charge is not among them.

LeeH

(published on 05/02/2009)

Follow-Up #1: More about neutrinos

Q:
deacay into an electron anti-neutrino? i am asking about an electron neutrino which travels through the human body and possibly alters velocity and direction of a moving human body through the neutrinos charge attraction to ion charges in cellular fluid causing deploarisations etc? If thois hypothesis was true the electron neutrino would have to have a charge, wouldnt it?
- MArc
Australia
A:
Dear Marc,
First of all, don't worry about the 50 Trillion neutrinos from the sun that pass through your body every second.  Their interactions with ordinary matter are so weak and infrequent  that you might get one or two during your lifetime.  If so, it would probably disrupt a single cell. No big deal.   Scientists who study solar neutrinos build detectors weighing tons and are lucky to get a handful of events per month.  Other naturally occurring  radioactive materials in the earth's crust are far more likely to interact and are more harmful to cells.  

Now about nomenclature.  Neutrinos associated with electrons are called electron-neutrinos because they are always associated with interactions containing electrons.  Muon-neutrinos are always associated with muons and tau-neutrinos with tau mesons.  These two latter types refuse to interact with electrons.  All three have zero charge.   You were concerned about neutrinos interacting without having charge.  Charge is not necessary for an interaction to happen.  For example both neutrons and gamma rays have zero charge but interact happily with other particles:  via the strong force and the first case and electromagnetic interactions in the second.  Neutrinos interact via the so-called weak force.      I recommend that you check out the web site:    for more information.

LeeH

(published on 05/10/2009)

Follow-Up #2: Does everything have to respect the law of mass energy equivalence?

Q:
Here comes a lay mans question. Does everything in the universe have to respect the law of mass energy equivalence? I know atoms respect this law but does this only work in a atoms or do particles also respect this law? Or because they are elementary and we dont know if their made up of a system we cant really tell if they abide to the law or not? For example if a neutrino has mass does that mean that it should contain some form of energy?
- Thapelo (age 30)
Gauteng,Johannesburg,South Africa
A:

Hello Thapelo,

As far as we can tell the answer is yes, we have no contrary experimental evidence.   Even far away galaxies show spectral lines and kinematical effects that seem to obey the general rules of special and general relativity as well as energy conservation.

Neutrinos can have both momentum and energy associated with their mass.   The full relativistic equation is E2 = m2 c4 + p2 c2 , where m is the mass and p is the momentum,  c is the speed of light.  Each component contributes to the total energy.

LeeH

 


(published on 10/13/2015)

Follow-up on this answer.