Transcript P.1 Energy for the home

Lesson.3: Uses of Static Electricity
Objectives
Be confident in explaining the following uses
of static electricity in some scientific detail.
Photocopiers
Dust Precipitators
Defibrillators
Paint Sprayers
Photocopiers
What do they do?
How it works
A Photocopier uses static charge to apply toner
(black powder) to the paper
1. A high
voltage
charged wire
transfers
positive
charge to the
drum
2.
The Drum becomes charged evenly
over its whole surface.
3.
Light removes charge from the parts
which are not to be printed.
4. Charge attracts toner particles.
5. Toner is rolled onto the page
6. Toner is melted onto the paper.
Summary
Precipator
Electrostatic Precipitators.
How does it work ?
Smoke particles become charged and are
attracted to plates and stick to them.
Completing the story…
The dirt particles clump together
What happens to the mass of clumps?
Get heavier
What force increases as mass
increases?
Gravity !
So what will happen eventually to the
large clumps?
Fall to the bottom
Furnace/boiler
Precipitator with 40cm wide
plate spacing on a
Cleaned 320-megawatt coal-fired
flue gas power boiler
Gas with particles
in from burning
coal in the furnace
Precipitated
particles collected
here
Precipitators
Write the missing words in the correct order
Plates in a precipitator are charged to a
high pd or ________.
Dirt particles become charged and are
attracted to the _________ charged plates.
The dirt sticks to these meaning the smoke
coming out is now ________.
As the dirt clumps up it becomes _______
enough to fall down the chimney.
heavy
oppositely
cleaner
voltage
Precipitators : Answers
Plates in a precipitator are charged to a
high pd or voltage
Dirt particles become charged and are
attracted to the oppositely charged plates.
The dirt sticks to these meaning the smoke
coming out is now cleaner
As the dirt clumps up it becomes heavy
enough to fall down the chimney.
heavy
oppositely
cleaner
voltage
The defibrillator
Saving your life!
What happens here?
What is Fibrillation ?
Normal heart rhythm
In some heart conditions the electrical impulses
which are necessary for the proper operation of
the heart fall into disorder
The heart chambers flutter rather than pulse
rhythmically.
Little or no blood will be pumped like this so the
sufferer is in mortal danger.
Trace showing ventricular
fibrillation
Defibrillation
In order to save the life of someone with a fibrillating
heart a defibrillator can be used.
Electrolyte gel is smeared on electrodes (known as
paddles) which are placed on the patients body either
Side of the heart.
A large voltage is applied across these electrodes to
drive a current through the patient’s heart. This current
can restore normal heart rhythms.
If a persons heart is showing no electrical impulses then
defibrillation will not revive them.
Safety
It is important when using a defibrillator that
no one touches the patient or any exposed
contacts on the defibrillator
Or else they may become the next patient!
A big enough electric shock can cause
defibrillation.
Defibrillation implant
Defibrillation
“When a heart is in disorder electrical paddles
can be connected and a charge given to restart it”
Questions
1. Why must there be a good contact between
the paddles and the patient ?
2. Why must the doctor be insulated from the
paddles ?
Paint Spraying
Summary of Paintspraying
The paint is charged as it comes out of the nozzle.
The paint spreads out in a spray due to repulsion
The car must be connected to the opposite voltage.
The paint is attracted to the oppositely charged car.
The paint is applied evenly all over
Static Electricity
True or False !
A photocopier works
because of
electrostatics.
TRUE
If an object loses
electrons, it becomes
negatively charged.
FALSE
It is important to connect
an aeroplane to its tanker
before refuelling.
TRUE
Paint from a paint sprayer
spreads out because all
the paint particles have
the same charge.
TRUE
Oil tankers are filled with
hydrogen before cleaning
to avoid explosions.
FALSE
The operator of a
defibrillator should be
attached to the patient
FALSE
To use a defibrillator it must
not be a connected to the
patient’s chest
FALSE
The dust collected from
dust precipitators clumps
together
TRUE
In the paint shop of a car
factory, the car body is
given the same charge as
the paint to make it stick
better.
FALSE
Soot particles stick to
the plates in a dust
precipitator.
TRUE
Complete
Higher
‘Static Electricity’ and ‘Uses of Static Electricity’
on pages 134 - 136.
Foundation
‘Static Electricity’
on pages 123 - 124.
Foundation MARK SCHEME
32
• Recognise and describe how static electricity can be useful:
• restarting a heart when it has stopped (defibrillator);
• photocopiers/laser printers (detailed structural knowledge
not required);
• removing dust from smoke in chimneys;
• paint spraying.
• Describe (Explain) how static electricity can be useful for
restarting the heart when it has stopped (defibrillator):
• paddles charged;
• good electrical contact with patient’s chest;
• charge passed through patient to make heart contract;
• care taken not to shock operator.
• Describe (Explain) how static electricity can be useful for
electrostatic dust precipitators to remove smoke particles etc from
chimneys:
• metal plates/grids put into chimneys;
• connected to a high PD;
• dust particles attracted to plate/grid;
• dust attracts together to form larger particles;
• dust falls back down chimney when particles are heavy
enough.
• Describe (Explain) how static electricity can be useful for paint
spraying:
• spray gun charged;
• paint particles charged;
• repel giving fine spray;
• object charged oppositely to paint;
• attracts paint;
• even coat, less waste, shadows painted