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UNIT 2 CELLS AND BATTERY

UNIT 2
2
...
1
...
The purpose of an electric cell is to convert chemical energy into
electrical energy
...
The primary difference between
a battery and a cell is a battery can be composed of a number of cells
...
For
example, the 9-volt batteries have 6 individual cells inside them
...
1
...
Such a cell is
shown in Figure 1, comprising copper and zinc electrodes
...
Other possible electrode pairs exist, including zinc-lead and zinc-iron
...
e
...
d
...
By knowing the
e
...
f
...
m
...
of any pair of metals may be
determined
...
1
...
Cannot be recharged
2
...
Can be used once

2
...
4

Secondary cell
1
...
Reversible
3
...

Table 1

Types of cells and batteries
a
...
Alkaline cell
c
...
Edison cell
e
...
2

Cell connections
2
...
1

Series connection
Assume that;
n = number of cells connected in series
E = e
...
f cell
R = external resistance
r = internal resistance of cell

Figure 2

So that:
a) Total emf, ET = nE Volts(V)
b) Total internal resistance, rT = nr Ohm(Ω)
c) Total resistance in the circuit, RT = nr + R
d)
GˍG˅ˊ FˋF
GGGFˌG
GˍG˅ˊ GFGˇGG˅ˌFF ˇˌ GˆF FˇGFGˇG
ˌ {ˀ{
{ {
ˌG - ʼ{é{

2
...
2

ʾ

ʼʾ

Parallel connection

Assume that;
m = number of cells connected in parallel
E = e
...
f cell
R = external resistance
r = internal resistance of cell
So that:
e) Total emf, ET = E Volts(V)
f) Total internal resistance , ”:

F

g) Total resistance in the circuit,  :
d)

Figure 3

GGGFˌG

F

-é

GˍG˅ˊ FˋF
GˍG˅ˊ GFGˇGG˅ˌFF ˇˌ GˆF FˇGFGˇG
{ˀ{
{ {
G
- ʼ{é{
ˋ

MAM/FI/JKE/POLISAS-ET101/UNIT 2

é

ʾ

ʼʾ

2

UNIT 2 CELLS AND BATTERY
2
...
3

Series-parallel combination
Assume that;
n = number of cell in series
m = number of cells in parallel
E = e
...
f cell
R = external resistance
r = internal resistance of cell
So that:
h) Total emf,ET = nE Volts(V)
i) Total internal resistance,rT

F

é
F

Figure 4

-é
j) Total resistance in the circuit, ˞
d)
GˍG˅ˊ FˋF
GGGFˌG
GˍG˅ˊ GFGˇGG˅ˌFF ˇˌ GˆF FˇGFGˇG
ˌ {ˀ{
{ {
ˌG
- ʼ{é{
ˋ

ʾ

ʼʾ

Example 1
One battery consists of three cells in series
...
E
...
f each cell is 1
...
2Ω
...

Solution:
Total e
...
f , E = nE = 3 X 1
...
5V
Total internal resistance = nr = 3 X 0
...
6Ω
Total resistance, RT = nr + R
= 0
...
6Ω
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MAM/FI/JKE/POLISAS-ET101/UNIT 2

3

UNIT 2 CELLS AND BATTERY
Example 2
Two cells with e
...
f 1
...
2Ω are joined in parallel and
connected to an external resistor of 4Ω
...

Solution:
Total e
...
f , E = 1
...
2/2 =
0
...
1 + 4
= 4
...
Four cells for each group and the group are joined in
parallel
...
5V and internal resistance is 0
...
One external resistor 5Ω
connected in parallel to the group
...
5) – 1
...
84V
@
VS = IRL = 0
...
84V

4

UNIT 2 CELLS AND BATTERY
TUTORIAL 1

1
...
Emf for each cells and internal resistance is 1
...
2Ω
...

2
...
5V and internal resistance 0
...

Calculate the value of current flow if the external resistance, 5Ω is joined to them
...
A battery consist of 12 cells are divided in three group which each group consist of four cells in
series
...
The emf of each cell is 1
...
2Ω
...
Calculate the current flow
...
A battery consists of five cells in series
...
5V and internal resistance is 0
...
A battery is
connected to the load resistance of 15Ω
...
Total e
...
f
ii
...
Total current
5
...
5V cells in series, each cells having an internal resistance of 0
...
Determine :
i
...
The potential difference at the battery terminals
...
One battery consists of four cells, connected in series
...
45V and internal
resistance of 0
...
if a load resistance of 5Ω is connected to the battery, draw the circuit and
calculate:
i
...
Total resistance
ii
...
Current flow
7
...
Emf and internal resistance of each cells is 1
...
4Ω
...

8
...
5V and 0
...
If the current flow through load resistance is 1
...

9
...
5V and internal resistance of 0
...
Draw the circuit and calculate:
i
...
Terminal voltage
10
...
45V and internal resistance 0
...
Load resistance 15Ω is connected to the battery
...


MAM/FI/JKE/POLISAS-ET101/UNIT 2

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