Lightning-Magnetism-Electrostatic force Science Grade 8

1. NATURAL PHENOMENA
DONE BY:ANAMIKA PRIYA,
AASHIR SALIM, RANIA
KURSHITH, AFSHA SALIM,
NOEL VARGHEESE

2. PRE-REQUIRED KNOWLEDGE:
1) Lightning is an electric spark on a huge scale.
2) It is caused by the accumulation of electric charges in the
clouds.
3) Electric charge is the property of matter which is
responsible for electrical phenomena
4) Electric charges exist in two forms: positive electric
charges(+) and negative elctric charges (-).
5) opposite charge attract and like charges repel.
6) A greek scientis called Thales observed that when a
material known as amber acquires electric charge on
rubbing with silk and that the force of this electric charge

3. ELECTRIC CHARGES

4. ELECTRIC CAHRGES
1. An object having electric charges is called a charges object
2. An object not having any electric charges is called an uncharged
object.
3. The process of giving electric charge to an object is called
charging the object.
4. In this context, the charging of an object by rubbing it with
another object is called charging by friction.
5. All the insulator objects can be charged by friction but all
conductor objects cannot be charged by rubbing while held in
hands.
6. when two objects are rubbed together both the objects get
electrically charge but they both have different charges ( + and -)

5. ELECTRIC CHARGES
• ACTIVITY 1:
• TAKE A SCALE AND A PICE
OF SILK CLOTH
• RUB THE SCALE ON THE
SILK CLOTH
• THEN TRY PLACING THE
SCALE OVER BITS OF
PAPER AND ALSO TRY
PLACING THE SILK CLOTH
OVER THE BITS OF PAPER,
THEY ALSO ATTRACTS.
• the glass rod was neutral
charged before being rubbbed
on a silk cloth. due to friction it
becomes electrically charged
and exerts pressure on
uncharged objects, here
paper.
• the glass rod will have positive
charge and the silk cloth will
have negative charge.

6. HOW IS IT DETERMINED WHICH OBJECT MUST HAVE WHICH
CHARGE?
WHETHER AN OBJECT BECOMES POSITIVELY CHARGED OR
NEGATIVELY CHARGED PURELY DEPENDS ON THE NATURE
OF THE MATERIAL OF AN OBJECT.
.?
• ALL THE OBJECTS
MADE OF PLASTIC
CALLED ACRYLIC (
SUCH AS BALLPEN
REFILL AND CLEAR
PLASTIC) GETS
POSITIVE CHARGE.
• ALL THE OBJECTS
MADE OF POLYTHENE
PLASTIC (NORMAL
PLASTIC ) .(SUCH AS
SHEET AND POLYTHENE
PLASTIC COMB) GET
NEGATIVE CHARGE.

7. PRE-REQUIRED KNOWLEDGE:
• ALL THE OBJECTS ARE
MADE UP OF ATOMS.
• ATOMS ARE MADE UP OF
PROTONS , NEUTRONS AND
ELECTRONS.
• NEUTRONS ARE
NEUTRALLY CHARGED
PARTICLES
• PROTONS ARE POSITIVELY
CHARGED OBJECTS
• ELECTRONS ARE
NEGATIVELY CHARGED
OBJECTS.
• THE PROTONS ARE
TIGHTLY PACKED IN THE
NUCLEUS .
• ONLY ELECTRONS ARE
TRANSFFERED IN
CONFIGURATION.
• THE ELECTRONS ARE
LOOSELY HELD.

8. HOW RUBBING OBJECTS CHARGES IT?
• In an uncharged object,the
number of positively
charged particles and
negatively charged
particles in the atoms are
equal.
• The equal number of
positive and negative
electric charges balance
each other and make the
object electrically neutral.
• When rubbed with each other, the
uncharged objects lose their
electrons hence the balance is
broken. these objects then become
positively chargd beacuse of the
higher number of protons in it.
• the object which gains the
discharged electrons during rubbing
becomes negatively charged.

9. PRE-REQUIRED KNOWLEDGE
• What is electrical
induction?
1. the process by which an
electrical conductor
becomes electrified when
near a charged body, by
which a magnetizable
body becomes
magnetized when in a
magnetic field or in the
magnetic flux set up by a
• ACTIVITY 3:
• a magnet when rubbed
against a safety pin
magnetises the safety pin.
• the safety pin cats and
behaves like a magnet for
some time.
• from this it is concluded
that a magnet can make
the atoms in a substance
move.

11. WHY A CHARGED OBJECT ATTRACTS AN
UNCHARGED OBJECT?
• A CHARGED OBJECT
ATTRACTS AN
UNCHARGED OBJECT
BY PRODUCING
OPPOSITE CHARGES IN
THE NEARER END OF
THE UNCHARGED
OBJECT BY ELECTRIC
INDUCTION.

12. STATIC ELCTRIC CHARGE
1. The electric charges
generated by friction are
static electric charges.
2. These elctric charges
remain bound on the
surface of the charged
objects.
3. Conductors cannot
pocess static electric
charges only insulators
can.
• Activity 2:
• when we rub our hands
friction is generated.
• but this frictionated hands
when brought near tiny
bits of paper it doesnt
attract them
• because it is skin which is
an insulator.

13. PRE-REQUIRED KNOWLEDGE:
• The bright flash of light
which we see in the clouds
is called lightning.
• lightning is an electrical
discharge in the
atmosphere between
oppositely charged clouds
(or between charged
clouds)
• a cloud is a visble mass of
condensed water vapours
• a heavy dark rain cloud is
known as storm cloud.
• lightning is of two types-
sheet lightning and fork
lightning.
• in 1752, benjamin franklin
proved lightning carries
elctricity.

15. HOW A SHEET LIGHTNING IS FORMED ?
Storm clouds formed → heavy winds formed move upwards
→ the water droplets in clouds rub against each other →
electric charge is formed between water droplets (smaller
water droplets↔ + charge & bigger water droplets↔ -
charge ) → smaller water droplets being lighter move
upwards within the cloud → amount of positive and
negative charges increase and meet with each other, they
produce an intense spark.......

16. HOW A FORK LIGHTNING IS FOMRED ?
• storm cloud passes over a building and induces ositive
charges on its top → the building becomes negatively
charged and the positive charges in the building flows
towards the clouds → the charges meet and spark
occurs.

18. DANGERS AND MEASURES TO PREVENT
LIGHTNING....
• LIGHTNING CAN CAUSE FIRE TO TALL BUILIDNGS AND CAN SET
TREES ON FIRE.
• LIGHTNING CAN BE PREVENTED USING LIGHTNING CONDUCTOR.
• AVOID STANDING IN OPEN SPACES DURING THUNDER STORM.
• STAY AWAY FROM UNCOVERED VEHICLES.
• NVER STAND UNDER OR NEAR A TREE OR BUILDING DURING
THUNDERSTORM.
• AVOID UMBRELLAS
• AVOID TOUCHING METAL PIPES
• AVOID USING ELECTRIC APPLIANCES.
• A PERSON MUST SQUAT LOW DURING THUNDERSTORM.
• SATY AWAY FROM POLES AND TOWERS.