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1. A SYSTEM OF
RESISTORS

2. CONTENT
INTRODUCTION.
RESISTOR OF SERIES.
DERIVATION OF RESISTOR OF SERIES.
DIAGRAM OF RESISTOR OF SERIES.
RESISTOR OF PARALLEL.
DERIVATION OF RESISTOR OF PARALLEL.
DIAGRAM OF RESISTOR OF PARALLEL.
APLLICATIONS OF RESISTOR.

3. INTRODUCTION
The current through a conductor depends
upon its resistance
And potential difference across its ends.
In various electrical
Gadgets, we often use resistors in various
combination. We now therefore intend to
see how Ohm’s law can be applied to
combination of resistors. There are two
type of resistors:-
Resistor of Series
Resistor of Parallel

4. RESISTOR OF SERIES
Series Circuits are sometimes called current-
coupled or daisy chain-coupled. The current in
a series circuit goes through every component
in the circuit. Therefore all of the
components in a series connection carry the
same current. There is only one path in a
series circuit in which the current can flow.
The formula to search resistance is
Rs = R1 +R2 +R3 +…….+Rn

5. DERIVATION OF RESISTOR OF SERIES
Given that
V= V1 + V2 +V3 (i)
I= the current
Applying the Ohm’s law to the entire circuit ,we have
V=IR
On applying Ohm’s law to the three resistors separately, we further
Have
V1=I R1
V2=I R2
V3=I R3
From equation (i)
I R= I R1 +I R2 +I R3
or
RS=R1 + R2 + R3
We conclude that when several resistor are joined in series, the
resistance of the combination Rs equals the sum of their individual
resistances, R1,R2,R3 and thus greater than any individual resistance

6. DIAGRAM OF RESISTOR OF SERIES
Electric circuit in which three resistors
having resistances R1, R2 and R3 respectively
are joined together in a series. Here the
resistors are said to be connected in series.

7. RESISTOR OF PARALLEL
Two or more components are connected in
parallel they have the same potential difference
(voltage) across their ends. The potential
differences across the components are the same
in magnitude, and they also have identical
polarities. The same voltage is applicable to all
circuit components connected in parallel. The
total current is the sum of the currents
through the individual components, in accordance
with KIRCHHOFF’s current law

8. DIAGRAM OF RESISTOR OF PARALLEL
Electric circuit in which three resistors
having resistances R1, R2 and R3
respectively are joined parallel to each
other. Here the resistors are said to be
connected as parallels.

9. DERIVATION OF RESISTOR OF PARALLEL
Given that
I=the total current
I= I1 +I2 +I3 (i)
RP be the equivalent resistance of the parallel
By applying Ohm’s law to the parallel combination of resistance we
have
I =V/RP (ii)
On applying Ohm’s law to each resistor, we have
I=V/R1; I2= V/R2; and I3 =V/R3 (iii)
From equation (i) to(iii) we have
V/RP= V/R1 + V/R2 + V/R3
or
1/RP= 1/R1 + I/R2 + 1/R3
We may conclude that the reciprocal of the equivalent resistance of a
group of resistances joined in parallel is equal to the sum of the
reciprocals of the individual resistance.

10. APLLICATIONS OF RESISTOR
The principle of resistors can be applied for
heating elements in iron, toasters, heaters,
and hair dryers which dissipate voltage as
heat. New generation auto motive LED lights
cluster, demand a specialist resistor solution.
Aluminum clad wire wound resistor provide
high power dissipation in a limited space and
are designed for direct heat sink mounting
using thermal compound
to achieve maximum
performance.

11. THANK YOU
Teacher's remark