Two electrons repel each other across completely empty space. Nothing joins them, and nothing touches. So how does the push get from one electron to the other?
You have already seen that light comes in particles, called photons. The photon has a second job. Electron A sends out a photon, and electron B absorbs it. Photons pass between the two electrons again and again, and each exchange pushes the electrons apart.
Attraction works by exchange too. A proton and an electron also exchange photons, and those exchanges pull the two together. So wherever the electromagnetic force acts, photons are passing between charged particles.
Two protons held near each other repel electrically. What passes between them as they exert this force?
Protons carry electric charge.
Charged particles interact by exchanging photons.
Photons pass between the two protons.
Which particle carries the electromagnetic force?
How do charged particles exert the electromagnetic force on each other?
Which force does the photon carry?
A charged sock clings to a wall. Which particle is exchanged between the sock's charges and the wall's charges?
An electron in an atom is attracted to the protons in the nucleus. Which particle carries that attraction?
Which particles interact by exchanging photons?