Topic 2: Resistivity and fundamentals of electricity
Objectives:
a. Define Resistivity
b. Define ohm’s law
c. Distinguish between DC and AC and their properties
characteristic
d. Describe the basic relationships of voltage, current and
resistance in a series circuit
e. Define ohm’s law
Reference:
1.Electricity 1, Devices, Circuits and Materials ;4th edition by Thomas Kubala
2. Fundamental of Electric Circuit 6th edition by Charles K. Alexander and Mathew O. Sadiku
3. Basic Electronics, 2nd edition by Crob
Note: Resistivity Problem Set ...Chapter 1 Resistances
DC- for commercial uses such as flashlights and power supplies for
electronic circuits
BOARD WORK
Use the White Board
Example No. 2
2. rho= 10.4 Ωcm/ft
L= 2 meters
Dia=30 mil
R?
Temperature coefficient of resistance
-Positive α all metals in their pure form have positive temperature coefficient. This
means that R increases with temperature.
-Change in resistance per unit resistance per degree change in temp.
α= ΔR
RO* Δt
R or RT=RO(+(1+α(t-to))
Where :
R or RT=Resistance at any temperature
RO= Resistance at 0 degrees at 32 degree Farenheit
to= Freezing point of H2O
T= any temp.
Example:
A tungsten wire has a 14 ohms R at 20 degrees
Celsius. Calculate its resistance at 120 degrees and
the alpha(α) is 0.005
Given: RO= 14 ohms
t= 120 degrees
to= 20 degrees
Solution:
R or RT=RO(1+α(t-to))
=14(1+0.005(120-20)
RT= 21 ohms
Horsepower and Watts
1 Hp= 746 watts = 550ft lbs/sec
Electric Energy
Energy work is done whenever power is used at a
definite time. Energy dispatched dependent on the
amount of power applied as well as the time consumed
performing certain task.
Energy= power x time
Unit: Watts*sec. = kWh
Introduction
Topic 1: Series and Parallel connection
Presented by
ENGR. ANDREW G. BITANCOR
FACULTY
DEPARTMENT OF ELECTRICAL ENGINEERING
Topic : Series and Parallel Connection
Objectives:
a. Define a series circuit and a parallel circuit connection
b. Describe the current flow and the operational differences
between series and parallel circuit
c. Connect and draw the a series and parallel circuit
Reference:
1.Electricity 1, Devices, Circuits and Materials ;4th edition by Thomas Kubala
2. Fundamental of Electric Circuit 6th edition by Charles K. Alexander and Mathew O. Sadiku
3. Basic Electronics, 2nd edition by Crob
Series Circuit- is one of which devices are connected
that there is one only one path for current to flow.
Characteristic :
1. The voltage across the circuit is the sum of the
voltages across each component
Series Circuit- is one of which devices are connected
that there is one only one path for current to flow.
Characteristic :
1. The voltage across the circuit is the sum of the
voltages across each component
Series Circuit- is one of which devices are connected
that there is one only one path for current to flow.
Characteristic :
2.Current through each component is the same
Series Circuit- is one of which devices are connected
that there is one only one path for current to flow.
Characteristic :
2.Current through each component is the same
Series Circuit- is one of which devices are connected
that there is one only one path for current to flow.
Characteristic :
3.The resistance increases as each load is added
Series Circuit- is one of which devices are connected
that there is one only one path for current to flow.
Characteristic :
3.The resistance increases as each load is added
Series Circuit- is one of which devices are connected
that there is one only one path for current to flow.
Characteristic :
4.If there is a break at any point in the circuit it will
break the flow of current
Series Circuit- is one of which devices are connected
that there is one only one path for current to flow.
Characteristic :
4.If there is a break at any point in the circuit it will
break the flow of current
Application of Series
Circuit
Parallel Circuit- It has two or more path for current to flow
Characteristic :
1. Voltage applied is the same across the branch
terminal
Parallel Circuit- It has two or more path for current to flow
Characteristic :
1. Voltage applied is the same across the branch
terminal
Parallel Circuit- It has two or more path for current to flow
Characteristic :
2. Current is the sum of the branch circuit
Parallel Circuit- It has two or more path for current to flow
Characteristic :
3.The resistance decrease as the load increases
Parallel Circuit- It has two or more path for current to flow
Characteristic :
4.If one bulb is disconnected, it will not affect the other
bulb
Application of Parallel
Application of Parallel
Application of Parallel
Application of Series
Application:Christmas
Light
Topic 3: Series and Parallel Circuit
Objectives:
a. Explain the characteristics of series circuit
b. Explain the characteristics of Parallel circuit
c. Demonstrate a procedure for solving series and
Parallel circuits
Reference:
1.Electricity 1, Devices, Circuits and Materials ;4th edition by Thomas Kubala
2. Fundamental of Electric Circuit 6th edition by Charles K. Alexander and
Mathew O. Sadiku
3. Basic Electronics, 2nd edition by Crob
Series Circuit- is one of which devices are connected
that there is one only one path for current to flow.
Characteristic :
1. Voltage applied to a series circuit are distributed
across the various components
2. The current is the same through out the circuit
Series Circuit
V1
V2
V3
Where: R Total Resistance
I = I1 = I2 = I3
RT= R1+ R2 + R3
T=
IT
VT
VT=V1+ V2+V3
T
In Summary Series Circuit
Parallel Circuit- It has one or more path for current to flow Characteristic :
1. Voltage applied is the same across the branch terminal
2. Current is the sum of the branch circuit
Resistance Total
1/RT=1/R1+ 1/R2
RT=
1
1/R1+ 1/R2
Where:
RT =total resistance
R1 = resistance of resistor 1
R2 = resistance of resistor 2
R3 = resistance of resistor 3
Parallel Circuit
VT
IT
I1
V1
I2
V2
1/RT= 1/R1+1/R2+R3
RT=
1
1 + 1+ 1
R1 R R
Where:
V3 V =V = V = V
T
1
2
3
IT= I1+ I2 + I3
I3
In Summary Series Circuit
Topic 4: Voltage Divider and Current Divider
Objectives:
a. Explain the characteristics of voltage divider
theorem as applied in electric circuit
b. Explain the characteristics of current divider
theorem as applied in electric circuit
c. Demonstrate a procedure for solving voltage
divider and current divider circuits
Reference:
1.Electricity 1, Devices, Circuits and Materials ;4th edition by Thomas Kubala
2. Fundamental of Electric Circuit 6th edition by Charles K. Alexander and
Mathew O. Sadiku
Current Divider Principle- Good for
parallel circuit only
IT
VT
I1
R1
I2
R2
Current Divider Principle- Good for
parallel circuit only
Where:
IT
VT
I1
R1
RT = R1XR2
R1+ R2
Substitute RT to equation 1
I1 = IT R2
R1 + R2
I2
R2
VT=(IT)( RT)
IT =I1 +I2
VT = V 1 + V 2
RT R1
R2
IT =I1 +I2
VT = V 1 = V 2
IT RT = I1 R1 = I2 R2
I1 = IT RT
R1
I2 = IT RT
R2
1
Voltage Divider Principle- Good for
Where:
series circuit only
IT =I1 = I2
V1 V2
V3
VT = V1 = V2 = V2
RT R1 R2 R3
V1 = VT R1
IT
VT
RT
V2 = VT R2
RT
V3 = VT R3
RT
Voltage Divider Principle- Good for
series circuit only
V1
IT
V2
VT
V3
Example 1
Two equal resistances draw 10A from 100V source
while connected in series. How much current will they
draw from the source if the resistances are connected
in parallel.
a. 10A
b. 20A
c. 30A
d. 40A
Example 1
Two equal resistances draw 10A from 100V source
while connected in series. How much current will they
draw from the source if the resistances are connected
in parallel.
Solution: R= V/I= 100/10= 10 ohm
For two equal R, then 10/2= 5 ohm of each R
-In parallel, two 5 ohm is equivalent to 2.5 ohm
I= 100/2.5 = 40A
RT=R1XR2= 5X5 = 25/10=2.5
R1+R2 5+5
1/RT=1/R1+ 1/R2
RT=
1
1/R1+ 1/R2
RT=
1
1/5+ 1/5
RT=2.5 ohm
Example 2
A resistor of 4 resistance of 4 ohms is connected
across a 120V supply. Another resistance of R ohms is
connected across the same supply and the total
current is 60 A. The value of R is.
a. 2
b. 3
c. 4
d. 5
Example 3. What resistance must be connected across
a 4-ohm resistor in order to give an equivalent
resistance of 3 ohms.
a. 8
b. 10
c. 12
d. None of these
Example No.4 . If two incandescent bulbs rated 110 V, 25
W and 110V, 100W are in series and connected across
220V source.
a. Both bulbs will give of their normal brightness
b. The bulbs will divide the voltage source equally
c. 25W watt bulb will be over voltage
d. 100W watt bulb will be over voltage