Electric field and Electric Potential

Electric field and Electric Potential
        Electric field is a region around a charge in which charge applies the electric force on other charges. The intensity of electric field at a point due to a charged body is a vector quantity so it will be having both magnitude and direction.
        The magnitude of intensity of electric field due to a point charge is the electric force acting on a unit positive test charge placed at that point.
             E=F/q. where q is a positive test charge which is kept at that point where the electric field is to be measured.Its SI unit is N/C i.e. newton/coulomb
            The direction of intensity of electric field is away from the charge when source charge is positive and towards the charge when the source charge is negative.
      Electric potential at a point in the electric field of a source charge is the work done in bringing a unit positive test charge from infinity to that point.It is scalar quantity. It is positive for positive source charge and negative for negative source charge.
             V=W/q  Its SI unit is J/C i.e. joule/coulomb
       

PHYSICS ASSIGNMENT FOR CLASS XI

Q1: WHAT IS THE SCOPE AND EXITEMENT OF PHYSICS? WRITE IN YOUR OWN WORDS.
Q2: DEFINE THE TERM UNIT FOR THE MEASUREMENT IN PHYSICS. WHAT TELLS THE  
       NUMERICAL VALUE IN ANY MEASUREMENT.
Q3: HOW MANY SIGNIFICANT FIGURES IN THE FOLLOWING:-
       (i) 250 metre (ii) 250 (ii) 2.50metre
Q4: DEFINE THE INSTANTENIOUS VELOCITY AT THE POINT.
Q5: DERIVE THE THREE EQUATION OF MOTIONS USING INTEGRATION METHOD.

Units and Dimensions

Physical Quantities:  In Physics we deal with different physical quantities.  We need to measure them. For the measurment  we compare the physical quantity with its some standard value  called 'Unit'. In any measurement we have two things (i) Numerical Value n and (ii) and its unit u. Numerical value tells that how many times the unit comes in particular measurement. The numerical value and unit of a physical quantity are related with each other as
                         n  α 1/u  i.e. nu=constant  ................................very Important


System of Units:- There are different systems used for the measurement of physical quantities like FPS, CGS and MKS.
   At present the system which is used SI System i.e. International Standard of Units. There are seven fundamental quantities and their units in SI Systems

 (1) LENGTH                                                           METRE
 (2) MASS                                                               KILOGRAM
 (3) TIME                                                                 SECOND
 (4) TEMPERATURE                                          KELVIN
 (5) ELECTRIC CURRENT                                AMPERE
 (6) LUMINOUS INTENSITY                           CANDILA
 (7) AMOUNT OF SUBSTANCE                      MOLE

 In addition to this, there are two more fundamental units  i.e. radian (Unit of Plane angle) and Steredian ( Unit of solid angle)

 Fundamental Quantities and their Units:- Fundamental means independent whether it is quantity or units.

One can not be converted into other .

 Derived Quantities and thier Units:-    The other physical quantites depend on fundamentals, called Derived quantities. So we can say that derived quantities are those which are derived from fundamental quantities and same for the Derived Units.

Example :- Area, Speed , velocity. acceleration. Force etc.

Dimensions:- Dimensions are the powers which are raised on fundamenal quantities  to express derived quantities.

Simple Harmonic Motion

SIMPLE HARMONIC MOTION

SHM is defined as such an oscillatory motion about a fixed point(known as mean position) in which a restoring force always act which is proportional to the displacement from mean position but opposite in direction

Coulomb's Law :- The electrostatic force between the two point charges is directly proportional to the product of their magnitudes and inversely proportional to the square of distance between them.
        Since force is a vector quantity so knowing its direction is most important.The direction of this force depends upon the nature of the two charges.Same nature charges repel while the opposite nature charges attract.