1. electric current and ohmic resistance
1.1. electric current
1.1.1. it is a flow electric charges between two terminal of conductor if there is a potential difference between its terminals
1.1.2. direction
1.1.2.1. conventional
1.1.2.1.1. it is the flow of electric charges from +pole to -pole
1.1.2.2. real
1.1.2.2.1. it is the flow of electric charges from -pole to +pole
1.1.3. conditions
1.1.3.1. potential difference between its terminals
1.1.3.2. electric source
1.1.3.3. closed circuit
1.1.4. good conductors
1.1.4.1. it has high concentration of free electrons
1.1.4.2. it has high conductivity
1.1.4.3. example
1.1.4.3.1. silver , copper and other metals
1.1.5. bad conductors
1.1.5.1. it has few number of free electron
1.1.5.2. it has low conductivity
1.1.5.3. example
1.1.5.3.1. glass and porcelain and gases
1.2. ohmic resistance
1.2.1. it is a type of opposition against the flow of electric charges duo to the friction force between the molecules of the conductor and electrons that causes loss of electric energy in form of thermal energy
1.2.2. thermal effect
1.2.2.1. harmful effect
1.2.2.1.1. in some electric instrument which causes
1.2.2.2. useful effect
1.2.2.2.1. in the instruments designed for converting the electric energy into heat energy
1.2.3. depend
1.2.3.1. length R&L at constant other factor
1.2.3.2. cross section Area R&1/A at constant other factor
1.2.3.3. type of matrial
1.2.3.4. tempreatre
1.2.4. rule , unit
1.2.4.1. R=P.L/A
1.2.4.1.1. R=V/I
1.2.4.2. ohm
1.2.4.2.1. volt / amp
1.2.5. main unit
1.2.5.1. ohm
1.2.6. note
1.3. specific resistance
1.3.1. It is the resistance of conductor when length is 1m and cross section area is 1m2 at given temperature
1.3.2. depend
1.3.2.1. Temperature
1.3.2.2. Type of material
1.3.3. Rule
1.3.3.1. P = L / R.A
1.3.4. Unit
1.3.4.1. Ohm . M
1.4. conductivity
1.4.1. It is the reciprocal of resistavity
1.4.2. depend
1.4.2.1. Temperature
1.4.2.2. Type of material
1.4.3. Rule
1.4.3.1. R.A / L
1.5. proplems
1.5.1. Ratio
2. simple electric circuit and ohms law
2.1. simple electric circuit
2.1.1. consists of
2.1.1.1. electric source
2.1.1.1.1. cell
2.1.1.1.2. battery
2.1.1.2. conductor
2.1.1.2.1. wires
2.1.1.3. key switch
2.1.1.4. ammeter
2.1.1.5. voltmeter
2.1.1.6. fixed resistance
2.1.1.7. variable resistance Rheostat
2.2. ohms law
2.2.1. the current intensity in a conductor is directly proportional to the potential difference across its terminals at constant temperature
2.2.2. electric current intensity ( I )
2.2.2.1. rule , unit
2.2.2.1.1. I=Q/t
2.2.2.1.2. C/sec
2.2.2.2. main unit
2.2.2.2.1. amp
2.2.2.3. i
2.2.3. potential difference between 2 points (V)
2.2.3.1. rule , unit
2.2.3.1.1. V=W/Q
2.2.3.1.2. J/C
2.2.3.2. main unit
2.2.3.2.1. volt
2.2.3.3. i
2.2.4. electric motive force of a cell e,m,f ( VB )
2.2.4.1. rule , unit
2.2.4.1.1. VB=W/Q
2.2.4.1.2. J/C
2.2.4.2. main unit
2.2.4.2.1. volt
2.2.4.3. i
2.2.5. work done ( energy lost ) ( W )
2.2.5.1. rule . unit
2.2.5.1.1. W=V.Q
2.2.5.1.2. V.C
2.2.5.2. main unit
2.2.5.2.1. Joule
2.2.6. Quantity of electric charges ( Q )
2.2.6.1. rule , unit
2.2.6.2. main unit
2.2.7. note
2.2.7.1. if the current intensity through a conductor increases
2.2.7.1.1. la \
3. التحويلات
3.1. length
3.1.1. v
3.2. area
3.2.1. v
4. connecting of resistors
4.1. paralel
4.1.1. experiment
4.1.2. note
4.1.2.1. connecting more resistors in parallel will decrease the total resistance in the circuit so the current intensity will increase and the power consumed will increase
4.1.2.2. the potential difference remains constant across all parallel resistors
4.1.2.3. the home electrical devices are connected in parell
4.1.2.3.1. d
4.1.2.3.2. c
4.1.2.3.3. c
4.2. experiment
4.3. series
4.3.1. note
4.3.1.1. connecting more resistors in series will increase the total resistance in the circuit so the current intensity will decrease
4.3.1.2. the current intensity remains constant in all series resistors
4.3.1.3. if you cut off any lamp all lamps in series resistoes will turnd off
4.4. proplems
4.4.1. تخمين التيار الكهربي
4.4.1.1. rule
4.4.1.1.1. any even number 1/2 resistors / 1/2 resistors
4.4.2. when you want to get current intensity in a one resistor or to get Values resistor occuping in parallel conaction
4.4.2.1. use Vpw = I 1 . R1
4.4.3. slope higher
5. ohms law for closed circuit
5.1. main rule
5.1.1. VB = IReq + Ir
5.2. internal reisitance (r)
5.2.1. it is the reistance in side of cell or battery
5.3. IReq
5.3.1. it is the potential difference across the resistance of external circuit OR the terminal voltage across thye source (vt)
5.4. Ir
5.4.1. it is the potential difference across the internal resistance of the source OR drop of voltage duo to the internal resistance
5.5. the relation bettween vb and v
5.5.1. VB = V + Ir
5.6. notes
5.6.1. when the two batteries are connected in same opposite direction and the main battery (high volt ) recharged other battery ( low volt )
5.6.1.1. ( VB1-VB2 /Req +r1 +r2 )
5.6.2. when the two batteries are connected in same direction the
5.6.2.1. ( VB1+VB2 /Req +r1 +r2 )
5.6.3. the terminal voltage is always smaller than the e.m.f by the value Ir which is called drop of voltage
5.6.4. V = Vb when
5.6.4.1. the circuit is opened that mean I = 0
5.6.4.2. the internal resistance of the source neglected that mean r = 0
5.7. experment
5.8. effciency of battery
5.8.1. rule
5.8.1.1. V/VB x 100
5.8.2. notes
5.8.2.1. h
6. kirchoffs law
6.1. KCL
6.1.1. scientiffic idea
6.1.1.1. law of consevation of electric charges