Elementary particles
Answers are for parents and teachers.
1
What is the minimum photon energy in keV to create an electron–positron pair? (511 keV)
1022
2
In annihilation giving two photons each has 0.511 MeV. What is the wavelength roughly? (hc = 1240 eV·nm)
2.4 pm
3
How many quarks are there in a ⁴He nucleus?
12
4
What is the charge of an antiproton?
−e
5
Why can the proton not strictly be called «elementary»?
The proton is made of three quarks, so it has an internal structure.