A Level Physics Practice Exam

What does the strong nuclear force primarily affect?

1. Electrons and protons

2. Neutrons only

3. Protons and neutrons

4. All particles in an atom

The correct answer is: Protons and neutrons

The strong nuclear force primarily affects protons and neutrons, which are collectively known as nucleons. This fundamental force is responsible for holding the nuclei of atoms together, overcoming the electromagnetic repulsion between positively charged protons. In the atomic nucleus, protons and neutrons interact via the strong nuclear force, which operates at very short ranges (on the order of one femtometer, or about the size of a nucleon). It is the strongest of the four fundamental forces, but it acts only over short distances, thus it is confined within the nucleus itself. By binding protons and neutrons tightly together, the strong nuclear force ensures the stability of atomic nuclei, allowing multiple protons to exist in close proximity despite their electrostatic repulsion. Although electrons are also part of an atom, they are influenced primarily by electromagnetic forces rather than the strong nuclear force. Therefore, the strong nuclear force is significant only among protons and neutrons within the nucleus. This distinction highlights why the correct answer specifically identifies protons and neutrons as the primary particles affected by the strong nuclear force.