Important Laws in Physics and Their Applications

Physical laws are the deductions extracted based on many years of scientific research, observations, and experiments that require persistent performance under different conditions to reach the premises, which can be quickly credited worldwide.

We all are aware that our world stands working on some principles which are drawn by our scientists in the form of specific physical laws.

Essential Laws of Physics are:

1. Archimedes Principle

A Greek mathematician, Archimedes discovered this principle in the third century B.C. It asserts that- when a body is partially or wholly submerges in a fluid, it undergoes an upward thrust which is equal to the weight of the fluid superseded by it, i.e. its apparent loss of weight is similar to the weight of the liquid supplanted.

The mathematical equation formulated by this law is:

Fb = ρ x g x V

Where,

Fb is the buoyant force

ρ is the density the fluid

V is the submerged volume

g is the acceleration due to gravity.

Applications of Archimedes principle are :

• Submarine,
• Hot-air balloon,
• Hydrometer.

2. Avagadro’s Law

Italian Scientist, Anedeos Avagadro was the developer of this law in 1811. It affirms that equal volume of all gases under the identical circumstances of temperature and pressure-containing equal number of molecules.

The mathematical equation formulated by this law is :

V ∝ n

V/n = k

Where V is the volume of the gas,

n is the amount of gaseous substance in moles and

k is a constant.

When the quantity of gaseous substance increases, the equivalent increase in the volume occupied by the gas is given by:

V1/n1 = V2/n2 = k, according to Avogadro’s law).

Applications of Avogadro’s law are:

• Balloons

When we blow up a balloon, we are filling more moles of air in the balloon, and so it expands.

• Tyres

When we pump air inside the deflated tyres, the amount of moles of gas inside the tyres gets increased, which increases the volume of the tyres.

• Human lungs

When we inhale, air flows inside our lungs and hence, they expand while on exhaling, the air flows from the lungs to surroundings; thus, the lungs shrink.

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3. Ohm’s Law

It affirms that the current travelling through a conductor between two points is directly proportional to the potential difference between the two points if the physical state and temperature etc. of the conductor remains constant.

The mathematical equation formulated by this law is :

I =V/R

where I is the current through the conductor in units of amperes, V is the voltage measured across the conductor in units of volts, and R is the resistance of the conductor in units of ohms.

Applications of Ohm’s law are :

• Ohm’s law helps us to determine voltage or current or impedance or resistance of a linear electric circuit if the other two quantities are known to us.
• It also makes the calculation of power simpler.

4. Coulomb’s Law (1738-1806)

The force between the two electric charges decreased to the quarter of its original value when the distance between them doubled. The SI unit of electric account “Coulomb” which derives its name after Charles Augustin de Coulomb, who discovered the law.

The mathematical equation formulated by this law is :

F ∝ q1q2/d2

where,

ε is absolute permittivity,

K or εr is the relative permittivity or specific inductive capacity

ε0 is the permittivity of free space.

K or εr is also called a dielectric constant of the medium in which the two charges are present.

Applications of Coulomb’s law are :

• To calculate the distance and force between the two charges.
• The strength of the electric field can be known with the help of coulombs law.
• To calculate the force on one point due to the presence of several points (Theorem of superposition).

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5. Stefan’s Law (1835-1883)

This law states that the total energy radiated from a black body is the same as the fourth power of its absolute temperature. It is related to the temperature of the blackbody to the amount of the power it emits per unit area.

The mathematical equation formulated by this law is :

ε = σT4

Where,

ε = P/A

Applications of Stefan’s law are :

• It determines the amount of heat radiated from the black body.
• Another application of the law is to convert temperature(K) to intensity units (W.m-2), i.e. power per unit area.

6. Pascal’s Law (1623-1662)

“With an increase in a certain amount of pressure to a fluid, the pressure change uniformly distributes itself without any loss”. Hydraulic machines like hydraulic press work on this principle.AtmosphericAtmospheric pressure decreases as height increases. The SI unit of pressure is ‘pascal’ which derives its name after Pascal, who discovered this law.

The mathematical equation formulated by this law is :

F = PA

Where,

F is the force applied

P is the pressure transmitted

A is the cross-sectional area

Applications of Stefan’s law are :

• Hydraulic Lift: It works on the principle of equal pressure transmission throughout a fluid (Pascal’s Law).
• The inside of the cylinders houses a fluid that cannot be compressed.
• Pressure applied at piston A is transmitted equally to piston B without any loss, which cannot be compressed on the use of the fluid. Piston B significantly serves as a platform to lift heavy objects like big machines or vehicles.
• Few more applications include a hydraulic jack and hydraulic press.

The braking system of most cars employs forced amplification.