Question

The strong force (select all that apply.) a) is only attractive. b) does not act on electrons. c) only acts over a few $\mathrm{fm}$. d) All of the above are true. e) None of the above are true.

Short answer

a) is only attractive. b) does not act on electrons. c) only acts over a few $\mathrm{fm}$. d) All of the above are true. e) None of the above are true. Answer: b) does not act on electrons and c) only acts over a few $\mathrm{fm}$.

Step-by-step solution

Statement a: is only attractive.

The strong force only pertains to the nucleons (protons and neutrons) inside the nucleus of an atom. It is responsible for holding these particles together in the nucleus. The strong force is attractive; however, it also has a repulsive component when the nucleons come very close to each other. It ensures that the nucleons are not so close together that they become unstable. Therefore, statement a is not true.

Statement b: does not act on electrons.

The strong force mainly acts on quarks, which are the constituents of protons and neutrons. Electrons, on the other hand, are part of the lepton family and are not affected by the strong force. Therefore, statement b is true.

Statement c: only acts over a few $\mathrm{fm}$.

The strong force is a short-range force; its influence decreases rapidly as the distance between the particles increases. Typically, the range of the strong force is around ${10}^{-15}\mathrm{m}$ to ${10}^{-16}\mathrm{m}$, which is a few femtometers (fm). Therefore, statement c is true.

Final Answer

Statements b and c are both true, so the correct answer is: b) does not act on electrons. c) only acts over a few $\mathrm{fm}$.

Key concepts

Nuclear Forces in Physics

In the world of physics, the forces that dictate the behavior and interaction of subatomic particles within the nucleus of an atom are known as nuclear forces. These forces are essential for understanding the stability of matter and the interactions that occur at the atomic level.

There are two primary nuclear forces to consider: the strong nuclear force, often referred to as the strong force, and the weak nuclear force, which is responsible for certain types of particle decay. The strong force, in particular, is regarded as one of the fundamental interactions in physics, playing a critical role in holding the atomic nucleus together.

While electrons, which orbit the nucleus, interact mainly through electromagnetic forces, the strong force does not influence them. Instead, it has a profound effect on the protons and neutrons inside the nucleus, collectively known as nucleons. This inter-nucleon force overcomes the repulsive electromagnetic force between protons, allowing the nucleus to exist in a stable state.

Properties of the Strong Force

The strong force is characterized by a set of unique properties that differentiate it from the other fundamental forces in the universe. It is the strongest of all fundamental forces, surpassing the electromagnetic force, the weak nuclear force, and gravity by a significant margin within its operative range.

• Attractive Nature: The primary role of the strong force is to bind protons and neutrons in the nucleus, hence it is predominantly attractive. However, it has a repulsive aspect at very short distances, which prevents the nucleons from crushing into each other under high pressure, a concept known as 'nuclear saturation'.
• Charge Independence: Unlike the electromagnetic force which depends on the charge, the strong force acts equally on protons and neutrons despite protons being positively charged and neutrons being neutral.
• Color Charge: The strong force operates through a property of quarks known as 'color charge,' not to be confused with visual colors, which is quite different from the electric charge relevant to electromagnetic interactions.

The strong force's ability to act indiscriminately on protons and neutrons, irrespective of their electric charge, is essential for the diverse composition of elements in the universe.

Interaction Range of Strong Force

The strong force exhibits a remarkably short range of influence relative to the other fundamental forces. Its effects are predominantly felt at distances of about 1 to 3 femtometers (fm), which corresponds to roughly 10^-15 to 10^-16 meters - the typical scale of a nucleus.

At these distances, the strong force is sufficiently powerful to overcome the repulsive electromagnetic force between the positively charged protons. Beyond this range, its influence diminishes rapidly, rendering it practically nonexistent at larger scales. This rapid decrease in strength with distance is why the strong force does not have any significant effects outside of the nucleus, highlighting its role as a truly 'nuclear' force.