1. 1
PHYSICS
MODULE
2. ELECTRICITY

2. TOPIC:
2 ELECTRICITY
2.1 ANALYSING ELECTRIC FIELD AND CHARGE
FLOW
CONTENTS:
1. CHAPTER HIGHLIGHT (30 MINUTES)
2. ACTIVITY (50 MINUTES)
2

3. 3. ASSESSMENT (40 MINUTES)
4. MARKING SCHEME(ANSWER KEY)
CHAPTER 2
ELECTRICITY
2.1 Analysing electric fields and charge flow
1. _____________________can be produced by rubbing an object (e.g. polytena rod)
with soft fabric.
2. The produced charge is static which is known as _____________________.
3. Symbol for the quantity and unit of electric charge.
Symbol for the quantity Symbol for the unit
of electric charge of electric charge, Coulomb
4. Type, symbol and value of a unit of electric charge
Type of charge Symbol Value of a unit ( Coulomb)
Positive charge (proton)
Negative charge (electron)
5. The relationship between the total of electric charge and the amount of electric charge.
3
Q = 1 C

4. The total of The amount of The value of a unit
electric charge electric charge of electric charge
( +1.6 x 10-19
C )
6. Example:
What is the amount of the electron needed to carry charge of 1 C ?
Formulae: Q = ne Given: Q = 1 C Find: n = ?
e = +1.6 x 10-19
C
Solution: Q = ne .’. n = Q
e
= 1
1.6 x 10-19
= 6.25 x 1018
electrons
7. Electric current is defined as the rate of ___________________.
8. Example:
If the current which flows through a bulb within a minute is 1.5 A. Calculate the electric charge
that has flowed within a minute.
Formulae: Q = It Given: I = 1.5 A Find: Q = ?
t = 1 minute
= 60 s
Solution: Q = It
= (1.5)(60)
= 90.0 C
4
Q = ne
Current = Rate of charge flow
i.e. Current = Charge flow
Time
Formulae:
I = Q » Q = It
t
Unit:
A = Cs-1
» C = As

5. 9. The relationship between the current flow and the electric charges.
The above set up designed to show that the electric charges which flow through a conductor
produce electric current.
10. An electric field is an area which if entered by a charged object, it will experience the
__________________ which is produced by a quantity of charge.
11. The paths of electric field of a positive charge can be represented by the electric force lines or
electric field lines.
12. The characteristics of the electric field line are:
(i) The lines begin from the positive charge and end at the negative charge.
(ii) The lines do not overlap.
(iii) The lines repel each other.
(iv) The lines intensity represents the electric field intensity.
13. The pattern of electric field lines depends on the pattern of charged object.
(a) single spherical (positive charge) (b) single spherical (negative charge)
5
galvanometer
Van de
Graaff
generator
Water tap
+-

6. (c) two spherical of same charges (d) two spherical of different charges
X = neutral point
(e) a positive spherical & a negative
plat
(f) two plats of different charges
14. The effect of the electric field upon the charges.
(i) A ping-pong ball coated with conducting material
Step Observation Explanation
(1) A Very High
Voltage source is
connected to the
plats
F1 F2
• Attraction force on
the ping-pong ball
from positive plat is
at the magnitude with
the attraction force
from negative plat,
6
- -0+ -0
+
X
-
+ -
+ -

7. The ping-pong ball remains
motionless
i.e. F1 = F2.
• The ping-pong ball is
neutral
(2) The ping-pong
ball is pulled until
it touches
negative plat
F
(i)
• When the ping-pong
ball touches the
negative plat, this
ball will receive the
electrons and will be
charged negative.
• This negatively
charged ball will be
pushed by the
negative plat and will
be attracted by the
positive plat
F
(ii)
The ping-pong ball oscillates back
and forth between the two plats
until the Very High Voltage source
is disconnected
• Once the ping-pong
ball touches the
positive plat, all of its
negative charges will
be neutralized.
• Further, the ball will
be positively charged
• This positively
charged ball will be
pushed by the
positive plat and will
be attracted by the
negative plat
• The ball later will
touch the negative
plat, and the
processes will be
repeated.
(ii) A candle flame
Step Observation Explanation
A Very High
Voltage source is
connected to the
• The heat energy
produces positive
and negative ions
7
- - - - -+
+ + +
+
-+
-
+
+
+

8. plats
The flame is not symmetrically
distributed
The flame is deflected more
towards the negative plat
around the candle
flame
• Positive ions which
are heavier will bring
more flame attracted
towards the negative
plat. This happens
because the positive
ions move rather
slow
• Negative ions
(electron) which are
lighter will occupy
smaller flame area
Assessments
Objective Questions
1. If a charge of 300 C flows through a bulb every 2 minutes. Calculate the current which
flows through that bulb.
A 2.0 A B 2.5 A C 150 A D 600 A
2. There are 5 x 1018
electrons flow through a bulb within 20 seconds. What is the value
of current flow ? ( Given e= 1.6 x 10-19
C )
A 40 mA B 0.8 A C 16 A D 80 A
Structure Questions
A. 1 Define the following terms.
(a) Electric current: __________________________________________________
__________________________________________________
8
+ -
Electric current is defined as the rate of charge flow.

9. (b) Electric field: __________________________________________________
__________________________________________________
2 Sketch the electric field lines showing the direction of the field.
(a) single spherical (positive charge) (b) single spherical (negative charge)
(c) two spherical of same charges (d) two spherical of different charges
9
- -0+ -0
+-
An electric field is an area which if entered by a charged object, it will experience the
electric force which is produced by a quantity of charge.

10. (e) a positive spherical & a negative
plat
(f) two plats of different charges
B. 1 Explain the effect of the electric field upon the charges in the following cases:
(i) A ping-pong ball coated with conducting material
(ii) A candle flame
10
Answer: 1 B 2 A
+
-
+ -

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