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Many well-known scientists speculate that there might be one formula to define all the laws and phenomena of physics. Why? Because almost every law, principle, theory, and observation made of the physical world shares some similarities. This similarity is observed as being analogous. In simple words, analogous means similar in comparison. In physics, comparisons can be made based on mathematical formulas, underlying similarities in carrying out calculations, and the underlying principles. 

The basis of the law can also be compared and, if found similar, can be deemed analogous. In general, if similarities are found between any two laws on any of the aforementioned basis, it is analogous to each other.

What are analogous laws?

As per Merriam-Webster dictionary, the meaning of analogous is anything that is and looks similar in comparison. For example, based on shape, we can say that an orange is analogous to the Sun. So analogous laws in physics mean those laws that are similar in mathematical form and theoretical model. Now, if the processes in physics are similar in comparison, then we call them analogous processes.

Analogous Laws in NEET Examination

For those students preparing for NEET, analogous laws are somewhat difficult and confusing questions to prepare for. It has been asked many times in the past and will be asked in the future. The question pattern is similar to what is given below:

Ampere’s law is analogous to—

It is followed by four options such as,

  1. Gauss’s law
  2. Coulomb’s law
  3. Gay Lussac’s law
  4. Newton’s law of gravitation

Among these, you have to choose one option. 

Ampere’s law and Gauss’s law

  • Ampere’s law: Imagine a current passing through a conductor. If the flow of current is kept constant, then Ampere’s law states that the integral of the closed-loop magnetic field generated by the current is proportional to the net current passing through the loop.
  • Gauss’s law: This law helps us to find out the net amount of charges inside a closed surface of a material. It says that the amount of electric flux or lines of electric force penetrating through the enclosed surface is proportional to the net electric charge of the surface.

Study of formulae

As per the statement of Ampere’s law, the total magnetic field denoted by ∮ Bδl is directly

Why are they analogous?

  • Both formulae are trying to find an integral sum of things. In the case of Ampere’s law, it is trying to find a magnetic field, and in Gauss’s law, it is used to find an electric field.
  • The underlying calculating concept of both formulae is similar.
  • The right-hand side of both equations is similar.

Potential Difference in Current and Change in Heat

  • Potential difference in current: The main principle behind the flow of current through a conductor can be simply explained as the difference between the potential volts. Potential voltage is an electrical force that causes the electrons to move from one end to another. When there is a deficit of electrons in one end of the conductor, it creates a potential difference, and the force causes the electrons to move to the deficit end. In doing so, the flow of current occurs.
  • Change in temperatures in heat transfer: When we heat one end of the iron rod to some degree, it is natural to feel the heat at the other end. The basic reason heat is transferred in the iron rod is because of the change in temperature between the two ends of the rod. Heat causes molecules to come into motion, this increases the temperature of the iron rod at one end but the temperature at the other is still the same. This causes the molecules to move from the hot end to the cold end, which causes heat transfer.

Study of formulae

 The rate of heat transfer is mathematically calculated as,

Q = KAΔT/ d

where,

Q = Rate of heat transfer per unit time

K = Thermal Conductivity of the material

A = Area of contact

ΔT= Change in Temperature Thot – Tcold

Change in potential difference in current is given by,

δv = δr δi

Where,

δv= Change in potential difference

δr= Resistance

δi = change in current

Why are they analogous?

  • Both processes are driven by changes in either temperature or potential difference.
  • Both processes talk about a flow of either current or heat.

Conclusion

There are a lot of examples of analogous laws, analogous systems, and analogous processes in physics. We discussed two very commonly asked questions on analogous laws and analogous processes and the underlying concepts behind why they are analogous to each other by studying the formulae of each of them. 

A little trick to solve analogous questions in the exam can be to check the mathematical formula of the given law with each of the options. The statement of the laws can also help in determining if the laws are analogous to each other or not.