Q. The known forces of nature can be divided into four classes, viz. gravity, electromagnetism, weak nuclear force and strong nuclear force. With reference to them, which one of the following statements is not correct?
- Gravity is the strongest of the four
- Electromagnetism acts only on particles with an electric charge
- Weak nuclear force causes radioactivity
- Strong nuclear force holds protons and neutrons inside the nucleus of an atom
Answer: (a) Gravity is the strongest of the four
Universal Forces (The Four Fundamental Forces)
- The Four Fundamental Forces of Nature are: Gravitational force, Weak Nuclear force, Electromagnetic force and Strong Nuclear force.
- The weak and strong forces are effective only over a very short range and dominate only at the level of subatomic particles. Gravity and Electromagnetic force have infinite range.
- Gravitational Force – Weakest force; but has infinite range. (Not part of the standard model)
- Weak Nuclear Force – Next weakest; but short range.
- Electromagnetic Force – Stronger, with infinite range.
- Strong Nuclear Force – Strongest; but short range.
- The weak and strong forces are effective only over a very short range and dominate only at the level of subatomic particles. Gravity and Electromagnetic force have infinite range.
- Strong Force
- The strong force is a fundamental force that acts between subatomic particles of matter. The strong force is what binds the quarks together in clusters to form more familiar subatomic particles such as protons and neutrons. The force originates from a property known as the color. This property has no connection with color in the visual world. Particles without color, for example, electrons, do not experience the strong force. But, particles with color such as quarks do experience the strong force.
- Electromagnetic Force
- The electromagnetic force, also known as Lorentz’s Force explains how stationary and moving charged particles interact with each other. It is known as an electromagnetic force because of the presence of the formerly distinct electric and magnetic force.
- The electric force acts between all charged particles whether they are moving or not. While magnetic force only acts between moving charged particles. This means that every charged particle whether moving or not gives off an electric field.
- Weak Nuclear Force
- While other forces hold things together, a weak nuclear force plays a greater role in making things fall apart. Although a stronger force than gravity, it is only effective at very short distances. The theory of weak nuclear force was first proposed by Enrico Fermi and was known at that time as Fermi’s interaction. Following are a few of the properties of weak force:
- It is the only kind of reaction that can change one kind of quark to other
- Weak forces are propagated by carrier particles that have significant masses.
- It violates parity-symmetry
- It violates charge-parity symmetry
- While other forces hold things together, a weak nuclear force plays a greater role in making things fall apart. Although a stronger force than gravity, it is only effective at very short distances. The theory of weak nuclear force was first proposed by Enrico Fermi and was known at that time as Fermi’s interaction. Following are a few of the properties of weak force:
- Gravitation
- Gravitational force is the weakest of all. It is the force that decides how much we weigh and how far a basketball travels when it is thrown before it returns to the surface. When two objects are gravitationally locked, their gravitational force is centered in an area that is not the center of either of the objects, rather at the barycentre of the system.
