Keplers’s Laws of Planetary Motion, Kepler's Law, Law of Orbits, Law of Areas, Law of periods

Image
  Keplers’s Laws of Planetary Motion: 1 st law ( Law of Orbits ): Every planet moves around the sun in elliptical orbit with the sun at one of the foci of the elliptical orbit. 2 nd   law ( Law of Areas): The line joining the planet to the sun sweeps over equal areas in equal intervals of time.                                                             Area of SAB = Area of SCD  2 nd   law tells us that a planet does not move with constant speed around the sun. It speeds up while approaching the nearest point called ‘ perigee’ and slows downs while approaching the farthest point called ‘ apogee’. therefore, distance covered on the orbit with in the given interval of time at perigee is greater than that at apogee such that areas swept are equal. 3 rd Law ( Law of periods): The square of the time periods of revolution of...
Post a Comment

ohms law, ohms law formulas, what is ohms law, ohms law equations, ohms law definition, define ohms law, Non Ohmic Conductor

                                                    Ohm’s Law

The relationship between voltage (V), the current (I) and resistance (R)  in a d.c. circuit was first discovered by German scientist George Simon *Ohm. This relationship is called Ohm’s Law and may be stated as under :

 The ratio of potential difference (V) between the end of a conductor to the current (I) flowing between them is constant, provided the physical condition ( e.g. temp. And pressure ) do not change i.e.

                                V/I  =  Constant = R

Where R is the resistance of the conductor between the point considered.

For example, if in Fig. (a) the voltage between points A and B volts and volts and current flowing is I amp, then v/i will be constant and equal to R, the resistance between points A and B. If the voltage is doubled up, the current will also be doubled up so that the ratio v/i remains constant. If we draw a graph between V and I, it will be a straight line passing through the origin as shown in fig (b). The resistance R between points A and B is given by slope of the graph i.e.

                      R   =  tanθ  V/I  =  constant

Ohm’s law can be expressed in three forms

                       I  =  V/R ;  V  =  IR ;  R  =  V/I

These formulae can be applied to any part of d.c. circuit or to a complete circuit. It may be noted that if voltage is measured in Volts and current in Amps, then resistance will be in Ohms.

 





Non Ohmic Conductor

 

Those conductor which don not obey ohm’s law ( v = IR) are called non ohmic conductor e.g. vacuum tubes, transistor, electrolytes, etc. A non ohmic conductor may have one or more of the following properties:

 


01.  The V - I graph is non linear i.e. V/I is variable.

02.  The V-I graph may not pass though the origin as in case of

an ohmic conductor.

03.  A non ohmic conductor may conduct poorly or not at all when the p.d. is reversed. The non linear circuit problems are generally solved by graphical methods.

 

Comments

Post a Comment

Please do not enter any spam link in the comment box.

Popular posts from this blog

Electric flux and Electric Flux derivation

Image
Electric Flux: " The number of Electric Field lines passing through a certain area is known as Electric Flux through that area." Note:- Electric Flux is a scalar quantity and electric flux symbol is ∅. Electric Flux formula Derivation: Electric flux passing through Vector da An electrical flux passing through the entire page Using formula Electric Flux formula Electric Flux dimensional formula Electric Flux unit 
Read more

Coulomb's Law definition and derivation

Image
Definition:- The magnitude of the electrostatic force of attraction or repulsion between two point charges is directly proportional to the product of the magnitudes of charges and inversely proportional to the square of the distance between them. The law was first published in 1785 by French physicist Charles-Augustin de Coulomb, and was essential to the development of the theory of electromagnetism, maybe even its starting point, because it was now possible to discuss quantity of electric charge in a meaningful way. Coulomb's Law Derivation:- We can show it with the following explanation. Let’s say that there are two charges q1 and q2. The distance between the charges is ‘r’, and the force of attraction/repulsion between them is ‘F’. Then F  ∝ q1q2   ••••••• (1) F  ∝  1/r2   •••••••(2) By the equation no. 1 and 2 F  = k q1q2/ r2 where k is proportionality constant and equals to 1/4 π ε0. where ε0 is absolute permittivity of free space. V...
Read more

Electric Dipole, Electric Dipole Moment, electric dipole moment dimensional formula

Image
Electric Dipole: An Electric Dipole is a pair of equal and opposite point charges separated by a short distance. q and -q are two equal and opposite point cahrges saparated by a small distance 2a Note:- The total charges of the electric dipole is zero, but this does not mean that the field of the electric dipole is zero. Electric Dipole Moment: Dipole Moment is a measure of the strength of electric dipole. Dipole Moment is equal to the product of the magnitude of either charge and the distance between then. Note:- It is a vector quantity whose direction is from negative charge to positive charge . S.I. Unit of Electric Dipole Moment = C.m Electric dipole moment dimensional formula:-
Read more