THE TEMPERATURE REMAINING CONSTANT THE CURRENT FLOWING IN THE CIRCUIT IS DIRECTLY PROPORTIONAL TO THE APPLIED VOLTAGE AND INVERSELY PROPORTIONAL TO ITS.

THE TEMPERATURE REMAINING CONSTANT THE CURRENT FLOWING IN THE CIRCUIT IS DIRECTLY PROPORTIONAL TO THE APPLIED VOLTAGE AND INVERSELY PROPORTIONAL TO ITS RESISTANCE.

V = I X R

I = V/R

R = V/I

OHM’S LAW FOR DC

IF V = 9 VOLT AND R = 10 OHMS

I = V/R = 9/10 = 0.9 AMPERE

IF I = 10 AMPERE V = 10 VOLT

R = I/V = 10 / 10 = 1 OHM

IF I = 10 AMPERE R = 5 OHMS

V = I * R = 10 * 5 = 50 VOLT

NUMERICALS BASED ON OHM’S LAW

KIRCHHOFF’S FIRST LAW

THE TOTAL CURRENT ENTERING THE CUIRCUIT (FLOWING TOWARDS) IS EQUAL TO THE TOTAL CURRENT LEAVING THE CUIRCUIT.

KIRCHHOFF’S SECOND LAW

THE TOTAL VOLTAGE DROP ACROSS THE RESISTANCE OF A CLOSED CIRCUIT IS EQUAL TO THE TOTAL VOLTAGE APPLIED TO THE CIRCUIT.

DIAGRAM KIRCHHOFF’S FIRST LAW

DIAGRAM KIRCHHOFF’S SECOND LAW

IT IS THE AMOUNT OF THE WORK DONE IN BRINGING ONE UNIT OF POSITIVE CHARGE FROM ONE POINT TO ANOTHER IN THE ELECTRIC FIELD.

THE VOLTAGE RATING IS MEASURE OF PRESSURE. THE AMOUNT OF PUSH BEHIND ELECTRIC CURRENT (EMF).

UNIT IS VOLT

POTENTIAL DIFFERENCE

THE RATE OF FLOW OF ELECTRON EQUAL TO ONE COULOMB PER SECOND.

AMPERE IS UNIT OF CURRENT.

AMPERE

ELECTRIC POWER (WATT)

WHENEVER ELECTRIC CURRENT FLOWS WORK IS DONE IN MOVING THE ELECTRONS THROUGH THE CONDUCTOR.

THE RATE AT WHICH THE WORK IS DONE IS CALLED POWER. THE BASIC UNIT OF POWER IS WATT.

P = V X IORP = I X I X R

1000 WATT = 1 KILO WATT ( ONE UNIT OF ELECTRICITY IS 1 KW HR )ONE HORSE POWER = 746 WATTS. ( ENERGY REQUIRED TO LIFT 33000 POUNDS OF WEIGHT TO 1 FEET OF HEIGHT AND KEEP IT THERE FOR 1 MIN.

WATT and DECIBEL

1dB = 10 Log WATTCONVERTING 100 WATT INTO DECIBELS

100 WATT = (10 log 100) dB= 10 *2= 20 dB

100 WATT = 20 dB, 1000 WATT = 30 dB

JOULE: UNIT OF WORK. ENERGY SPENT IN ONE SECOND BY AN AMPERE FLOWING THROUGH ONE OHM.

ENERGY: THE STRENGTH OR CAPACITY REQUIRED TO DO WORK. POWER MEASURED OVER A TIME (KW HR)

RESISTANCE IS THE OPPOSITION OFFERED BY A MATERIAL TO THE FLOW OF ELECTRON.

IN A CIRCUIT RESISTANCE IS USED TO REGULATE FLOW OF CURRENT AND ALSO TO GENERATE HEAT AND LIGHT AT CERTAIN OCCASION

THE UNIT OF RESISTANCE IS OHMS.

1000 OHMS = 1 KILO OHMS1 AMPERE = 1000 MILI AMPERE1 MICRO VOLT = 1/1 000 000 VOLT

RESISTANCE

RESISTANCE COLOUR CODE AND CIRCUIT SYMBOL

RESISTANCE COLOUR CODE AND CIRCUIT SYMBOL

RESISTANCE COLOUR CODE

B BLACK = 0B BROWN = 1R RED = 2O ORANGE = 3Y YELLOW = 4G GREEN = 5B BLUE = 6V VOILET = 7G GREY = 8W WHITE = 9

B B ROY GREAT BRITAIN VERY GOOD WIFEFIRST AND SECOND COLOUR ARE DIGITS.THIRD COLOUR IS NO OF ZEROSFOURTH COLOUR IS TOLERANCE

RESISTANCE COLOUR CODE

B BLACK = 0 B BROWN = 1R RED = 2 O ORANGE = 3Y YELLOW = 4 G GREEN = 5B BLUE = 6 V VOILET = 7G GREY = 8 W WHITE = 9

FOURTH COLOUR IS TOLERANCEGOLD = 5% SILVER = 10% NO COLOUR = 20%31 OHMS= FIRST COLOUR WILL BE ORANGE

SECOND COLOUR WILL BE BROWNTHIRD COLOUR WILL BE BLACK

RESISTANCDE IN SERIES

R = R1 + R2 + R3

RESISTANCDE IN PARALLEL

1/R = 1/R1 + 1/R2 + 1/R3

IF R1 = 20 OHMSR2 = 30 OHMSR1 = 40 OHMS

IN SERIESR = R1 + R2 + R3R = 20 + 30 + 40 = 90 OHMS

IN PARALLEL1/R = 1/R1 + 1/R2 + 1/R31/R = 1/20 + 1/30 + 1/40 = 6/120 + 4/120 + 3/120 = 13/120R = 120/13 = 9 OHMS APPROX

NUMERICALS : RESISTANCE

An RLC circuit (also known as a resonant circuit, tuned circuit, or LCR circuit) is an electrical circuit consisting of a resistor (R), an inductor (L), and a capacitor (C), connected in series or in parallel. This configuration forms a harmonic oscillator.Tuned circuits have many applications particularly for oscillating circuits and in radio and communication engineering. They can be used to select a certain narrow range of frequencies from the total spectrum of ambient radio waves. For example, AM/FM radios typically use an RLC circuit to tune a radio frequency. Most commonly a variable capacitor allows you to change the value of C in the circuit and tune to stations on different frequencies. Other practical designs vary the inductance L to adjust tuning.An RLC circuit is called a second-order circuit as any voltage or current in the circuit can be described by a second-order differential equation for circuit analysis.

Series RLC with Thévenin power sourceIn this circuit, the three components are all in series with the voltage source.

Series RLC Circuit notations:V - the voltage of the power source (measured in volts V)I - the current in the circuit (measured in amperes A)R - the resistance of the resistor (measured in ohms = V/A);L - the inductance of the inductor (measured in henrys = H = V·s/A)C - the capacitance of the capacitor (measured in farads = F = C/V =

A·s/V)q - the charge across the capacitor (measured in coulombs C)

Given the parameters v, R, L, and C, the solution for the charge, q, can be found using Kirchhoff's voltage law. (KVL) gives

                                                    For a time-changing voltage v(t), this becomes

Parallel RLC circuit

Parallel RLC Circuit notations:V - the voltage of the power source (measured in volts V)I - the current in the circuit (measured in amperes A)R - the resistance of the resistor (measured in ohms = V/A);L - the inductance of the inductor (measured in henrys = H = V·s/A)C - the capacitance of the capacitor (measured in farads = F = C/V =

A·s/V)

The complex admittance of this circuit is given by adding up the admittances of the components:

IMPEDENANCE DESCRIBES A MEASURE OF OPPOSITION TO ALTERNATING CURRENT.

IT IS COMBINATION OF RESISTANCE, CAPACITIVE REACTANCE AND INDUCTIVE REACTANCE

IT CAN BE CALCULATED BY OHM’S LAW

I = E/Z

OHM’S LAW FOR AC

RESONANCE IS A SPECIAL FREQUENCY IN AC CIRCUIT DETERMINED BY VALUE OF RESISTANCE , CAPACITANCE AND INDUCTANCE.

IN SERIES RESONANCE IS GIVEN BY MINIMUM IMPEDENCE AND ZERO PHASE.

IN PARALLEL ROSONANCE IN MAXIMUM, WHEN INDUCTANCE AND CAPCITANCE ARE EQUAL AND 180 OUT OF PHASE.

IT CAN BE CALCULATED BY

F = ½ PI UNDERROOT LC

OHM’S LAW FOR AC

IMPEDENANCE DESCRIBES A MEASURE OF OPPOSITION TO ALTERNATING CURRENTIT IS COMBINATION OF RESISTANCE, CAPACITIVE REACTANCE AND INDUCTIVE REACTANCEIT CAN BE CALCULATED BY OHM’S LAW

I = E/Z

FUSE

IT IS CURRENT RATED.

IT IS INSERTED BETWEEN ELECTRICAL SUPPLY AND EQUIPMENT TO PROTECT IT FROM GETTING DAMAGED.

IF CURRENT FLOW IN THE CIRCUITS EXCEEDS THE RATING. IF EQUIPMENT NEEDS 500 M A FUSE ( ½ A) IS INSERTED.

CIRCUITS BREAKER ARE ALSO USED AS PROTECTION FROM OVER LOADS. IF CURRENT INCREASES, IT JUMPS AND BREAKS THE CIRCUIT.

CELL IS A DEVICE WHICH CONVERTS CHEMICAL

ENERGY INTO DIRECT CURRENT

COMBINATION OF CELLS IS KNOWN AS BATTERY

CELLS CAN BE CONNECTED IN SERIES OR

PARELLEL

SERIES : VOLTAGE ADDS UP CURRENT

REMAINS THE SAME

PARALLEL : CURRENT ADDS UP VOLTAGE

REMAINS THE SAME

CELL

BATTERIES ARE RATED IN AMPERE HOUR (AH)

5 AH BATTERY CAN GIVE CURRENT OF 1 AMPERE

FOR 5 HOURS OR 5 AMPERE FOR 1 HOUR. BUT IT

CAN NOT GIVE 10 AMPERE FOR HALF HOUR DUE

TO BATTERY INTERNAL RESISTANCE

RATING OF A BATTERY

CIRCUIT DIAGRAM CELL

DRY CELLS ARE KNOWN AS PRIMARY CELLS

VOLTAGE IS 1.5 VOLT (ONE TIME USE TYPE)

CARBON ROD IS +VE

CONTAINER IS ZINC –VE

AMMONIUM CHLORIDE IS ELECTROLYTE

ADVANTAGE : CHEAP TO MASS PRODUCE

DISADVANTAGE : CAN NOT BE RECHARGED AND IF

LEFT UNUSED FOR SOME TIME, IT DETORIATES

TYPES OF CELLS : PRIMARY

SECONDARY CELLS CAN BE RE CAHRGED

TWO TYPES OF SECONDARY CELLS ARE

LEAD ACID

NICKEL CADMIUM

CELLS : SECONDARY CELL

VOLTAGE IS 2 VOLT

LEAD PEROXIDE IS +VE

LEAD OXIDE IS –VE

DILUTED SULPHURIC ACID IS ELECTROLYTE

SPECIFIC GRAVITY WHEN CHARGED 1.25 TO 1.35

SPECIFIC GRAVITY WHEN DISCHARGED FALLS TO

1.17.

SPECIFIC GRAVITY IS MEASURED BY HYDROMETER

TOPPING UP IS DONE BY DISTILLED WATER

SECONDARY CELLS : LEAD ACID

ADVANTAGE

CAN BE RECAHRGED

DISADVATAGE

BATTERIES DISCHARGES IF KEPT UNUSED FOR A

LONG TIME

CHARGING HAS TO BE CAREFULLY MONITORED BY

CHECKING VOLTAGE AND SPECIFIC GRAVITY

OVERCHARGING IS A PROBLEM

BOTH VOLTAGE AND SPECIFIC GRAVITY IS

CHECKED FOR DETERMINING IF A BATTERY IS

DISCHARGED.

LEAD ACID : ADVANTAGE / DISADVANTAGE

VOLTAGE IS 1.2 VOLT UNDER VARYING

LOAD

NICKEL HYDROXIDE IS +VE

CADMIUM IS –VE

POTTASIUM HYDROXIDE (KOH) IS

ELECTROLYTE

SECONDARY CELLS : NICKEL CADMIUM

ADVANTAGE

RUGGED, NON SPILLABLE

NOT DAMAGED IF UNUSED FOR A LONG

TIME

OVER CHARGING AND DISCHARGING DOES NOT

AFFECT MUCH

USED IN AIRCRAFT

NICKEL CADMIUM : ADVANTAGE / DISADVANTAGE

INVERTOR

AN INVERTOR IS AN ELECTRONIC DIVICE TO

CONVERT DC TO AC

BATTERY POWER IS USED FOR EMERGENCY

SUPPLY

BATTERY OUTPUT WHICH IS DC IS CONNECTED

TO INVERTOR. THE OUTPUT IS FED TO

EQUIPMENTS

INDUCTOR

A COIL OF WIRE USED TO SUPPLY INDUCTANCE

IN THE CIRCUIT.

VOLTAGE WHICH IS GENERATED IS CALLED

INDUCED EMF

INDUCED EMF OPPOSES ANY CHANGE IN THE

CURRENT WHICH INDUCED IT.

UNIT IS HENRIES AND SYMBOL IS L

SERIES : L = L1 + L2 + L3

PARALLEL : L = 1/L1 + 1/L2 + 1/L3

INDUCTOR IN SERIES

L = L1 + L2 + L3

RESISTANCDE IN PARALLEL

1/L = 1/L1 + 1/L2 + 1/L3

INDUCTOR

IF L1 = 20 HENERIESL2 = 30 HENERIESL1 = 40 HENERIES

IN SERIESL = L1 + L2 + L3 L = 20 + 30 + 40 = 90 HENERIES

IN PARALLEL1/L = 1/L1 + 1/L2 + 1/L31/L = 1/20 + 1/30 + 1/40 = 6/120 + 4/120 + 3/120 = 13/120L = 120/13 = 9 HENERIES APPROX

NUMERICALS : INDUCTOR

CAPACITOR

TWO CONDUCTING PLATE SEPERATED BY

INSULATING MATERIAL (DIEELECTRIC) CONSTITUTES

A CAPACITOR

AC WILL FLOW NOT DC

UNIT IS FARAD

SERIES : 1/ C = 1/C1 + 1/C2 + 1/C3

PARALLEL : C = C1 + C2 + C3

IN VARIABLE AIR CAPACITOR AIR IS DIELECTRIC

F = 1 / 2R UNDER ROOT LC

IF C1 = 20 FARADC2 = 30 FARADC1 = 40 FARAD

IN SERIES1/C = 1/C1 + 1/C2 + 1/C31/L = 1/20 + 1/30 + 1/40 = 6/120 + 4/120 + 3/120= 13/120L = 120/13 = 9 FARAD APPROX

IN PARALLELC = C1 + C2 + C3 L = 20 + 30 + 40 = 90 FARAD

NUMERICALS : CAPACITOR

DIODE

TRIODE

A triode is an electronic amplification device having

three active electrodes. The term most commonly

applies to a vacuum tube (or valve in British English)

with three elements: the filament or cathode, the

grid, and the plate or anode. The triode vacuum tube

is the first electronic amplification device.

TRANSISTOR : PNP & NPNA transistor is a semiconductor device used to amplify and

switch electronic signals. It is made of a solid piece

of semiconductor material, with at least three terminals for

connection to an external circuit. A voltage or current applied to one

pair of the transistor's terminals changes the current flowing

through another pair of terminals. Because the controlled

(output) power can be much more than the controlling (input)

power, the transistor provides amplification of a signal. Some

transistors are packaged individually but many more are found

embedded in integrated circuits.

The transistor is the fundamental building block of

modern electronic devices, and its presence is ubiquitous in modern

electronic systems.

PNP NPN

CATHODE RAY TUBE

TRANSFORMER

TRANSFORMER IS A DEVICE USED IN AN AC

CIRCUIT EITHER IN TO STEP UP OR STEP DOWN THE

VOLTAGE

FOR CHANGING VOLTAGE IN DC CIRCUIT CELLS

HAVE TO BE CONNECTED IN SERIES AND IN

PARALLEL

DUE TO THE EASE WITH WHICH AC VOLTAGE CAN

BE CHANGED, AC IS BEING ALL OVER THE WORLD

50 HZ IS USED IN DOMESTIC SUPPLY TO PREVENT

LINE LOSSES AND 400 HZ IS USED IN AIRCRAFT

TO REDUCE THE SIZE OF TRANSFORMER /CHOKES

GENERATORS / MOTORS

GENERATOR IS A MACHINE WHICH CONVERTS

MECHANICAL ENERGY INTO ELECTRICAL ENERGY IS

CALLED GENERATOR

A GENERATOR DESIGNED TO PRODUCE AC IS

CALLED AC GENERATOR OR ALTERNATOR

A GENERATOR DESIGNED TO PRODUCE DC IS

CALLED AC GENERATOR

COMMUTATOR IS USED TO CONVERT AC TO DC

MOTOR IS A MACHINE WHICH CONVERTS

ELECTRICAL ENERGY INTO MECHANICAL ENERGY IS

CALLED GENERATOR