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FORM 5Physics: Electricity
ANALYSING ELECTRIC FIELDS AND CHARGE FLOW
1.Where does charge
come from?
2. Unit of electric
charge?
3. Electric current?
Activity 1
Aim
Apparatus
Procedure 1.Start the motor of a _______________________ generator for a few minutes to produce
positive charges on the metal dome of the generator.2.Bring your finger close to the dome of the generator. Observe what happens
3.Touch the dome of the generator with the free end of the wire that is connected to the
microammeter. Observe the microammeter needle closely.
Observation 1._________________________________________________________________________
2._________________________________________________________________________
3._________________________________________________________________________
4._________________________________________________________________________
Conclusion
Describe an electric
field.
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4.To map the electric
field around metal
electrodes.
Draw the patterns of the electric field.
Describe the effect of
an electric field on a
charge Method.
A charged ball in an electric field.
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Describe the effect of
an electric field on a
charge Method.
The effect of an Electric field on a Candle Flame.
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RELATIONSHIP BETWEEN ELECTRIC CURRENT AND POTENTIAL DIFFERENCE
Describe Potential
Difference?
Definition of Potential
difference.
Potential difference
equation.
What is1 Volt?
How to measure
potential difference?
How to measure
current?
Solve problems
involving
W = QV
1. In a closed circuit, a 6 V battery is used to drive 40 C of electric charge through a
light bulb. How much work is done to drive the electric charge through the bulb?
2. If 72 J of work has to be done to carry 6 C of charge across two parallel metal
plates, what is the potential difference across the metal plates?
Describe the
relationship between
current and potential
difference.
State Ohms Law
Sketch a Graph ofV
against I
What isohmic
conductor and non-
ohmic conductor?
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Define Resistance? The resistance (R) of a conductor is defined as the ratio of the ________________________
across the conductor to the ___________________ flowing through the conductor.
Resistance formula
Good & poor
resistance?
A good conductor has a ____________ resistance and a poor conductor has a ___________
resistance.
Advantage of resistance In a light bulb, the current flowing through a resistance filament causes it to become ______
and then _____________.
Disadvantage of
resistance
Resistance causes some of the electrical energy to turn into__________________ , so some
electrical energy is _______________ along.
Ohms Law equation?
Aim of experiment? To determine the relationship between the potential difference and the electric current
flowing through an______________ and____________________________ conductor.
Hypothesis: The Iflowing through an ohmic conductor is directly proportional to V. It is not
proportional when flowing through an non-ohmic conductor.
Apparatus:
1.
2.3.
4.
5.
6.
7.
Tabulation by drawing
Graph V-I
Ohmic Conductor Non- Ohmic Conductor
Obey Ohms Law Not obey Ohms Law
Factors that affect
resistance?
1.
2.
3.
4.
a)Length factor For conductors of the same material and
cross-sectional area, the resistance R is
_________________ proportional to its length, l
:.where, Rlb)Cross-sectional factor For conductors of the same material and length,
the resistance R is __________________ proportional to its
cross-sectional area, A.
:. Where R lA
c)Type of material
factor
The resistance of a wire depends on
the _________________________
it is made from.
d)Temperature factor For conductors of the same material, length and cross-sectional area, the resistance R
generally __________________________ with temperature.
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Solve problems
involving potential
difference
A current of 0.5 A flows through a length of resistance wire when a potential difference of
12 V is applied between the ends of the wire.
(a) what is the resistance of the wire?
(b) What is the I flowing through the wire if the Vis increased to 15 V?
Resistance ofmetal
and semiconductor?
-The resistance of a____________
increases with temperature
-The resistance of a____________
decreases with temperature.
What is s.w.g number
of wire?
Super-conductor? A superconductor is a material whose
Resistance becomes_____________ when its
temperature ____________ to a certain value
called the ______________________
Advantage of
superconductor?
To maintain a current with no applied voltage at that temperature.
Able to sustain large currents
Smaller power loss during transmission
Less heat energy is wasted
Small-sized motors and generators can be used.
Example of material Element Critical temperature (K)
1. Zinc (Zn)
2. Aluminium (Al)
3. Tin (Sn)
4. Mercury (Hg)
5. Lead (Pb)
6. Niobium (Nb)
Example of
equipment that using
superconductor.
a)MAGLEV trains(Magnetic-levitation). Train can float on superconducting magnets.
b)MRI scanner (Magnetic resonance imaging) is used as diagnostic tool in medicine.
c)Electrical power line (superconductor cable) will increase the efficiency of electrical power
d)To produce computer chips which is small and faster
SERIES AND PARALLEL CIRCUITS
Identify series circuits In a series circuit, two or more resistors are connected one end after another toform a _______________________ path for current flow.
The bulbs share the __________________ from the battery, so each glows dimly.
The brightness of each bulb is _______________ the same since the same current
flows through each bulb.
If one bulb is removed, the other ______________ because the circuit is broken.
Identify parallel circuits All the components are connected with their corresponding ends joined together
to form _____________________________ paths for current flow.
Each bulb gets the full _______________________ from the battery because each
is connected directly to it. So each bulb glows brightly.
The brightness of each bulb in a parallel circuit is ______________ than those in a
series circuit with the same number of bulbs.
If one bulb is removed, the other keeps ________________ because it is still part
of an unbroken circuit.
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Determine the effective resistance of resistors connected in series and parallel.
Series Circuit Parallel Circuit
Diagram
Using Ammeter
Using Voltmeter
Using Ammeter
Using Voltmeter
Current
Potential Difference
Resistance
Brightness of light bulb
Solve the problems
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