# Laws of Physics Physics laws are, by definition, specified facts that have been deduced and extracted from empirical observations. In simple terms, the world around us functions predictably, and physical laws categorise behaviour. Physical laws are essentially inferences resulting from years of empirical findings and experimentation repeatedly replicated under various conditions to draw widely agreed conclusions. The scientific community continues to validate these over the period.

There are two types of fundamental physics laws that control our universe. Classical physics is concerned with ourselves, our surroundings, and the visible universe. But apart from this one, atomic physics is concerned with subatomic particles and their interactions. Various physics laws are the law of refraction, Maxwell relation, Coulomb’s law, Ohm’s law, thermodynamics, Newton’s law, etc.

## Derivations of physics laws

There are many ways from which the laws of physics are derived.

### ●      Definitions lead to physics laws.

Few scientific laws, such as the uncertainty principle, the principle of stationary action, or causality, are developed from mathematical definitions. These laws are empirical instead of mathematical, and they actually describe what we see through our five senses.

### ●      Laws developed from Symmetry theories.

The mathematical implications of spacetime and other symmetries are estimated to construct basic physical laws. For example, when the symmetry of time shifts, energy conservation emerges as a result. The conservation of momentum is produced from the symmetry of space.

### ●      Mathematical Symmetries-Induced Laws

The rotational symmetry of spacetime is expressed in the Lorentz transformation. The homogeneity of space is reflected in the conservation laws, and the uniqueness of electrons is reflected in the Pauli exclusion principle and other mathematical symmetries observed in nature.

### ●      Laws obtained from Approximations

Approximation laws are laws that are developed from approximations.

Some of our physical laws are formed by modifying or changing general laws. Newtonian dynamics, for example, are special reactivity under low-speed approximations. In a low-mass approximation, general relativity is Newtonian Gravitation; however, when large distances are involved, Quantum Electrodynamics is estimated by Coulomb’s law.

## Explanation for few physics laws

### 1.    Ohm’s law

Ohm’s law is one of the most fundamental and essential laws in electric circuits. It implies that if all physical conditions and temperature remain unchanged, the voltage across a conductor is directly proportional to the current. Mathematically  the relationship between current and voltage can be expressed as,

 V = IR

Where

• V = Voltage across the conductor
• I = Current flowing through the conductor
• R = Resistance of the conductor

### 2. Archimedes’ principle

The upward buoyant force exerted on a body immersed in a fluid, whether partially or wholly submerged, is proportional to the fluid’s weight that the body displaces and acts in the upward direction at the displaced fluid’s centre of mass, as per the Archimedes’ theory. The Archimedes law states that the buoyant force on an object equals the weight of the fluid displaced by the object in its simplest form. Mathematically expressed as,

 Fb = g ✕ V ✕ ρ

Where,

• Fb – Buoyant force
• g – Acceleration due to gravity
• V – Submerged volume
• ρ – Density the fluid

Many instruments follow the laws of Archimedes principles. For an incense lactometer, it determines the density of milk about water.

### 3. Newton’s laws of motion

The three Newton laws of motion explain how objects behave while they are stationary, moving, or when forces are applied to them.

Newton’s first law – states that a body at rest or in uniform motion will remain at rest or in uniform motion until and unless it is subjected to a net external force.

Newton’s second law – The acceleration of an object caused by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the object’s mass, according to Newton’s 2nd law.

Newton’s third law – According to Newton’s third law, every action has an equal and opposite reaction.