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Weber's Law

Last updated date: 19th May 2024
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Weber is a famous scientist who has given the law for physio psychology in the 19th century. It has become a great advancement in the field of physics as well as psychology. The law gave a way to introduce several innovations and principles to simplify human efforts. Let us explore more about what is Weber's law, its equation, and related terms in the equation in detail.

What is Weber's law?

Weber's law states that the just noticeable difference in stimulus intensity may affect the production of sensations proportionally. 

In simple terms, we can say that the size of the intensity of stimuli will show a proportionate change in producing the sense experiences.

\[\frac{\Delta I}{I}=k\]

Where ΔI(Delta I) represents the difference threshold, I represents the initial stimulus intensity and k signifies that the proportion on the left side of the equation remains constant despite variations in the I term.

It is denoted by Delta I. Where is the intensity of stimuli? And K is Weber's Constant.

Fechner Weber Law 

After Weber's law, Fechner's law became an interference of the Weber salah. According to Fechner's law, the intensity of our sensations may increase according to the logarithm of the energy but not change drastically. By merging these two statements, finally we got Fechner Weber's law.

Weber's law equation

According to Weber's law, the size of noticeable differences in stimuli may affect the increase in production of the census. This can be denoted by Delta S. 

dS = K*S

Where S is the reference stimuli

and K is constant.

, Also Weber's law equation can be written as,

 Ψ = k logS

Where Ψ = sensation

             K = constant

             S = stimuli.

Weber's Fraction

As the weather states that the relation between both the intensity and sensations are proportional to each other, the equation can also be expressed as a fraction. This fraction is known as Weber's fraction.


The Weber and Fechner law can be explained by using a simple experiment. 

And let us assume that you have lifted and a whole day weight of 3.0kg.  It requires an effort to hold 3.0kgs. Then, the minimal weight in between 3.0kg to 3.1kg weight is added, for say 0.05 kg, we may not observe much difference. But, it keeps on increasing gradually, the effort also increases. This noticeable difference gives Weber's law equation and fraction. 

According to Weber Fechner's law physics, substitute the values.

 The weight of magnitude, I = 3.0 kg, the increment threshold I = 0.3 kg.

The ratio of I/I for a given instance is

         0.3/3.0 = 0.1. 

This is Weber's Law.

Thus Weber's equation will be proved for different instances. One can verify by changing the weights.

Hence, the fraction I/I is known as the Weber fraction.


The Weber Fechner law has proven several things. But an exception has declared that it is not true for all cases. To avoid this exception, Weber's law has been modified a bit. This modified law can be expressed as,

\[\frac{\Delta I}{I+a}=K\]  

Here, K = Weber's Constant

          I = Intensity

          a = constant.

But the lower case letter represents the constant for the baseline. 

Weber's Law Perception

Both Weber and Fechner had made experiments and proved that the just noticeable difference can produce the noticeable difference in perceptions. This perception is nothing but Weber's law perception. Here we have different perceptions. Namely - 

  • Weight Perception:- Weber's law completely holds good for weight perception. It was already proven that the ratio of intensity is always one for several weights.

  • Vision Perception:- The Weber Fechner law provides all over a making relationship for the brightness of an eye. The magnitude of eye brightness can be easily calculated on the logarithmic scale and can be substituted in Weber's law equation or fraction.

  • Sound Perception:- unfortunately the weber doesn't hold good for sound perception. Particularly for loudness and increasing loudness, the weather's law cannot find the magnitude and fails to get a similar value. 

These are the various Weber's law perceptions and the results differ for each perception. 


Hence, Weber's law is an equation that states that the just noticeable difference can be proportional in producing the intensity of stimuli. If this relationship is expressed using the logarithmic scale, then it is called a Fechner law. So, both scientists have given a hypothesis for psychophysics. and bought the laws are interrelated with each other.

FAQs on Weber's Law

1. What are the Applications of Weber's Law?

Ans. Along with the human senses, Weber's law also results in various fields. It has several applications in different sectors. The major applications of Weber's law are as follows- 

Numerical Cognition:- several psychological studies have proven that calculating the discrimination of numbers which makes changes and reduces or increases the value. In that case, the weather's law explains psychologically and uses the logarithmic scale to calculate the difference between numbers even if they are continuously repeated.

Finance For the Public:- public finance is a new sector that uses Weber's law to calculate and understand demand and production. It is a newly developed literature hypothesis. It is a recent enhancement and new era in the literature with the hypothesis of both Weber and Fechner.

Pharmacy:- it is not an ecstasy that Weber's law is also used in pharmacy. According to pharmacology, the dosage of the medicines will be proportionate based on the severity of the injury or infection. 

In this way, there are several applications of Weber's law in various sectors.

2. Explain Weber's Law Concept Briefly With an Example From Our Daily Routine?

Ans.  It is easy to explain Weber's log concept that the just noticeable difference of stimuli intensity has a proportional change of producing sensations noticeably. This can be explained by using a simple and general example. One should get excited and interested to learn the concept. 

 Let's take the morning freshener as an example. If we consider a cup of tea that has a single spoon of sugar, it tastes good. If the sugar was added continuously in a negligible amount, one should feel a drastic change and intensity in taste. The disproportionate relation between the sugar and taste bud is nothing but Weber's law if these calculations can be done using a logarithmic scale, then it is called Fechner's law.