Rate of flow of electric charge through any point of the circuit is called electric current. Unit – ampere.
Current :- Flow of charge in conductor is called current.
Coulomb's law:-According to this law, the force of attraction or repulsion between stationary point charges is directly proportional to product of the charges and inversely proportional to square of distance between them.
Where K = 9 X
Electric field: It is the region surrounding an electric charge or group of charges, in which another charge experiences a force of attraction or repulsion.
Electric lines of forces:-An electric lines of force field along which a free isolated unit positive charge moves.
(1) Electric lines of force start from positive charge and end to the negative charge.
(2) No two lines of force can intersect each other because if they do so, then at the point of intersection two tangents can be drawn which would mean two directions of force at that point which is impossible.
(3) These lines have a tendency to separate from each other in the direction perpendicular to their length.
(4) Lines of force of uniform field are parallel.
(5) Lines of force leaves the surface of conductor normally.
Electric Flux: It is defined as that total number of lines of force passing normally through a curved surface placed in the field or the dot product of and normal.
1 unit = Volt-meter
OHM's law: According to this law if there is no charge the physical state of conductor (Such as temp.) then the current flowing through the conductor is directly proportional to the voltage applied i, e.
I αV .
A graph between applied voltage and current is a straight line shows that it follows ohm's law.
Note:- Ohm's law is valid for metallic conductors only.
Resistance :- It is property of
ρ = specific resistance or resistivity.
Note:- The reciprocal of resistivity is called conductivity.
(Ohm – m)–1 = mho/meter.
(1) T - ,R- because heat causes atoms in the crystal lattice to vibrate more.
(2) Resistance increase an a material become more disordered.
(3) Best lean → conductor silver, Tungsten → light bulb filament Nichrome → Heater element in toaster.
COLOUR CODE FOR RESISTANCES:
NOTE:- B. ROY Great Britain Very Good Wife.
Rate of charge of potential w.r.t distance in called potential gradient.
Electric Potential Energy: The electric potential energy of a system of charges is the work that has to be done in bringing these charges from infinity to near each other to form the system.
The potential energy of a system of charges q1 and q2 separated by a distance 'r' is
CAPACITOR: An element in which energy is stored in the form of electrostatic field is called capacitor.
Capacitance: Defined as ratio of charge given to the plate of capacitor to the pot. diff produced between the plate.
Area of Plane
D → Distance between the planes.
∈0 = 8.85 x 10-12
∈0 = Permittivitty of free space.
Unit – c2N–1 M–2
For a capacitor, v ∝ q
Energy stored in capacitor
It is an element in which energy is stored in the form of electromagnetic field (Unit → Henry.)
Energy stored in Inductor:
Inductance results from the fact that a flow of current produces magnetic field, according magnetic field along tends to induce a voltage (or current) in a wire according to Faraday's law.
For RL Load :
V=Vm sin wt
show I lags by 90º R-L Load phasor :-
For RC Load:
Shows I leads by 90º
For RC phases:
For RLC Load:
Case 1: |VL| > |Vc|
Case 2: |VL| < |Vc|
Case 3: |VL| = |Vc|
V = VR
Ø = 0
CosØ = 1(UPF)
Note:- Reactive power is consumed by energy storing demands.