OHM’S LAW FOR DC
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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
description
OHM’S LAW FOR DC. 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. NUMERICALS BASED ON OHM’S LAW. IF V = 9 VOLT AND R = 10 OHMS - PowerPoint PPT Presentation
Transcript of OHM’S LAW FOR DC
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
