Physics: 5. Moments
Syllabus
OP9 Investigate the law of the lever; recall two everyday applications of levers
Student Notes
A lever is a rigid object which is free to turn about a fixed point called a fulcrum.
Everyday applications of levers
Seesaw, scissors, door handle, wheel-barrow, spanner, etc.
(Can you identify the fulcrum in each case?)
The Moment of a force = the force × distance (between the force and the fulcrum).
Example
A force of 75 N is used to turn the spanner in the diagram. If the distance between the force and the nut is 10 cm
calculate the moment of the force.
Answer
Moment = Force x distance
= 75N × 0.1 m
=7.5 N m
What would be the effect of using a longer spanner?
The Law of the Lever:
When a lever is balanced, the clockwise moment acting on it is equal to the anti-clockwise moment
acting on it.
Experiment: To Verify the Law of the Lever
Procedure:
1. Hang a metre stick from the 50 cm mark as shown.
2. Attach two weights and adjust their positions until the metre stick balances.
3. Note the position and force of each object.
4. Show mathematically that the force multiplied the distance clockwise equals the force multiplied by the distance
anti-clockwise.
Maths Problems
Law of the Lever questions
1
Exam Questions
1. [2007]
Give an everyday example of an application of the lever, using a labelled diagram, showing the fulcrum and at
least one force acting on the lever.
2. [2008 OL]
The crowbar in the diagram acts as a lever
and applies a turning force on the boulder
(large rock).
Answer the questions which follow with
reference to the points A, B and C in the
diagram.
(i) Which of the three points, A, B or C, is the
fulcrum (the point about which the turning force acts)?
(ii) At which of the three points, A, B or C, will the least force be needed to move the boulder?
Give a reason for your answer.
3. [2008]
State the law of the lever.
4. [2007]
Define moment of a force.
5. [2007]
The diagram shows a metre stick suspended from its centre of
gravity.
A force of 3 N acts on the stick at the 90 cm mark and a force
of F newtons acts on the stick at the 20 cm mark. The metre
stick is balanced horizontally.
Calculate force F.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Other Test Questions
What is a lever?
Give two examples of a Lever
Define the term ‘Moment of a Force’.
A wrench 30 cm long is used by a mechanic to turn a nut. If the force he exerts on the end is 5 Newtons, calculate
the moment of the force.
State the Law of the Lever
A boy held a book of weight 50 Newtons in his fully outstretched hand, at a distance of 50 cm away. Calculate the
moment of the force.
A wrench 50 cm long is used to turn a nut. If the force exerted on the other end of the wrench is 20 N calculate the
moment of the force.
List two ways in which an object can be made more stable.
Draw a diagram of a scissors and indicate where the fulcrum is.
Beyonce weighs 500 N and is sitting at one end of a see-saw which is 4 m long and balanced in the middle. Jordan
is 2000 N. Where should she sit in order to balance the see-saw?
A metre stick is balance in the middle and has a force of 8 N hanging from the 20 cm mark. What force needs to
hang from the 60 cm mark in order to balance the metre stick?
2
Physics: 6. Centre of Gravity
OP8
Syllabus
Find the centre of gravity of a thin lamina
Investigate the role of centre of gravity in design for stability and equilibrium
Student Notes
The Centre of Gravity of an object is the point through all the weight of the object appears to act.
Expt: To find the centre of gravity of a sheet of cardboard.
1. Set up as shown.
2. Draw a line to represent the position of the cord.
3. Rotate the sheet of cardboard and repeat.
4. The intersection of the two lines represents the centre of gravity of the object
Stability
An object can be made more stable by:
(i) giving it a low centre of gravity
(ii) giving it a wider base
An object will topple if a vertical line through its centre of gravity falls outside its base.
Demonstration
Try to balance an empty coke can on its lip – it can’t be done because the centre of gravity is not over the lip.
Now pour a little water into the coke can and try again. This time you should be able to balance it because the water
results in the can having a new centre of gravity which is now directly over the lip.
Be able to answer all questions from this chapter in the workbook and textbook
Test Questions
1. Define the term ‘Centre of Gravity’.
2. When is an object in stable equilibrium?
3. Give two ways in which an object can be made stable.
4. What factor determines whether an object which has been tilted will fall over?
5. Describe briefly how to find the exact centre gravity of an irregular-shaped piece of cardboard (make sure you
include a diagram in your answer).
6. Explain why the centre of gravity of a double-decker bus should be as low as possible.
3
Physics: 7. Pressure
Syllabus
OP10 Understand the relationship between pressure, force and area; perform simple calculations using this
relationship
OP11 Investigate the relationship between pressure and depth for a liquid
OP12 Show that air has mass and occupies space
OP13 Understand that the atmosphere exerts pressure and that atmospheric pressure varies with height
OP14 Examine weather charts to observe variations in atmospheric pressure and relate these to weather conditions
Student Notes
Force
Pressure × Area
Pressure is caused by a force that pushes against an object.
The pressure increases when the force increases or when the area (that the force is acting on) decreases.
The unit of pressure is the pascal (Pa).
You can also use the N/m2 or N/cm2.
Example 1:
The wind exerts a horizontal force of 1000 N on a wall of area 20 m2. Calculate the pressure at the wall.
Answer: P = F ÷ A = 1000 ÷ 20 = 50 pascals.
Example 2:
A lady weighs 800 N and is standing in a pair of stiletto heels, each of area 2 cm2.
An elephant weighs 27000 N and the total area of its feet is 1800cm2.
Which exerts more pressure on the ground – the lady in stilettos or the elephant?
Answer
Total pressure exerted by the lady’s (two) feet = 800 ÷ 4 = 200 N/cm2
Total pressure exerted by the elephant’s (four) feet = 36000/1800 = 20 N/cm2
The lady exerts ten times more pressure on the ground than the elephant.
Pressure in Liquids: the pressure in a fluid increases with depth.
Demonstration
Set up as shown.
The water coming out of the bottom hole travels the farthest, because it is under
the greatest pressure.
4
Air has mass
Demonstration
Weigh an empty plastic bottle (with the top on) and note the mass.
Pump air into it using a special pump and weigh it again. Note the new mass.
Result: there was an increase in mass as a result of pumping air in, therefore air has mass.
Air occupies space
Demonstration
Glue some cotton wool to the bottom of a glass (inside).
Turn the glass upside down, submerge it completely into a large bowl of water and then remove it again.
Notice that the cotton wool is still dry.
Conclusion: the water could not enter the glass because there was air already in there.
The atmosphere exerts pressure
The atmosphere is made up of giggling atoms and exerts a huge amount of pressure on all objects, including the earth.
Demonstration
Use a large metal drum and pump the air out using a vacuum pump. The drum will collapse (implode) because there is
now a greater pressure outside acting inwards than there is inside acting outwards.
Atmospheric pressure varies with height
Atmospheric pressure decreases as the height above sea level increases (because there is less air overhead).
A barometer measures atmospheric pressure
Atmospheric Pressure and the weather
Areas of high atmospheric pressure are represented on a weather
chart by the letter H and will normally have dry, clear, settled
weather.
Areas of low atmospheric pressure are represented on a weather
chart by the letter L and will normally have cloudy, windy, wet
weather.
Why is low atmospheric pressure associated with bad weather?
Low atmospheric pressure means that it is easy for water to
evaporate into the air (because the ‘blanket’ of atmospheric
pressure pressing down on the water is lighter)
This results in more clouds and therefore more rain.
We will see when we study the chapter on Heat that water boils at 100 0C at atmospheric pressure. Can you
guess why it will boil at less than 100 0C if the atmospheric pressure is low?
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Exam Questions
1. [2006 OL]
(i) Complete the equation in the box using the words on the right.
(ii) Name the piece of equipment used to measure pressure.
2. [2009 OL]
Answer the following questions about pressure.
(i) Complete the equation in the box below using the words on the right.
Pressure =
(ii) If a metal block applies a force of 20 N on an area of 5 cm2, find the
pressure being applied by the block.
Area
Force
Area
Force
3. [2009 OL]
The diagram shows a container with three spouts. The container is filled with water.
Jets of water pour out of the spouts.
Why does the jet of water from the bottom spout travel the furthest out from the
container?
4. [2007]
The diagram is an Atlantic weather chart.
(i) Use the chart to predict two weather conditions that you might expect for
Ireland.
(ii) Explain why low atmospheric pressure causes one of the weather
conditions that you have given.
5. [2009]
Rib cage
The diagram shows a model of the human breathing
Diaphragm
system.
(i) Name the part of the breathing system represented by the balloons.
(ii) Choose from the list on the right the correct word to complete the sentence
below.
The part of the breathing system represented by the bell-jar is the
______________ .
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Other Test Questions
1. Calculate the pressure exerted by an object of weight 27N on the ground, if the area of its base is 3m2.
2. Draw a labelled diagram of the set-up used to demonstrate Atmospheric Pressure.
3. Complete the sentence; Pressure increases with ___________.
4. What is the relationship between weather and Atmospheric pressure?
5. Name an instrument used to measure atmospheric pressure.
6. Calculate the pressure exerted on the floor by a wooden box, which weighs 48 Newtons if the dimensions of the
base of the box are 2m by 4m.
7. An army tank can travel across wet land if it has tracks on, but not if it is on wheels. Explain why.
8. Draw a labelled diagram of the apparatus you would use to show that pressure in a liquid increases with depth.
Include in the diagram the results you would expect to see.
Pressure and boiling point
9. How would you demonstrate that pressure affects boiling point?
10. What is the effect of increased pressure on the boiling point of water
11. Why does increased pressure affect the boiling point of water?
Can you think of an application of this (a device which is built on this principle)?
Can you think of anyone where this might be a problem?
7
Physics: 8. Work, Energy and Power
Syllabus
OP15 Define and give the units for work, energy and power, state the relationship between work and power, and
perform simple calculations based on this relationship
OP16 Classify sources of energy as renewable or non-renewable
OP17 State the principle of conservation of energy
OP18 Explain why the sun is considered our primary source of energy and how this is important in food production
and energy supply
OP19
List the advantages and disadvantages of different energy sources, including nuclear sources of energy, as
part of the solution to national energy needs
OP20 Identify different forms of energy and carry out simple experiments to show the following energy
conversions:
a. Chemical energy to electrical energy to heat energy
b. Electrical energy to magnetic energy to kinetic energy
c. Light energy to electrical energy to kinetic energy
OP21 Give examples of energy conversions from everyday experience.
Student Notes
Work
The unit of work is the joule (J).
Work done = Force × distance
Energy
The unit of energy is also the joule.
Energy is the ability to do work
Power
Power is the rate at which work is done
Power
The unit of power is the watt (W)
Energy × Time
The sun is our primary source of energy.
This means that almost of our energy came about either directly or indirectly from the sun.
For example fossil fuels were formed from decaying plants and animals.
These plants and animals relied on the sun either directly (plants) or indirectly (animals eat plants or other animals that
ate plants) for their survival. So essentially, fossil fuels contain the captured energy of the sun from millions of years
ago.
Sources of Energy: renewable and non-renewable
Energy sources can be divided into two groups – renewable and non-renewable.
A renewable source of energy can be replenished in a short period of time.
A non-renewable source cannot be replenished in a short period of time.
Examples of renewable sources are solar energy, wind energy, wave energy etc (see table below)
Examples of non-renewable energy are fossil fuels (peat, coal, oil etc) which can take millions of years to form.
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Non-renewable energy sources
Original source
Advantages
Disadvantages
Fossil fuels
Fuel can be stored.
Relatively cheap.
Increases greenhouse effect.
Limited supply of fuel available.
Nuclear energy
Very little greenhouse gas emissions.
You can get a lot of energy from a
very small amount of fuel.
Possibility of nuclear accidents.
Not easy to dispose of the waste.
In Ireland 90% of electricity is generated by burning fossil fuels compared to other European countries that have an
average of 50% use of fossil fuels and a 30% use of fossil fuels in the USA.
Renewable energy sources
Original source
Solar energy
Advantages
Costs little to run
Wind energy
Costs little to run
Hydroelectric energy
Wave energy
Costs little to run
Costs little to run
Tidal energy
Biomass energy
Geothermal energy
Costs little to run
Costs little to run
Costs little to run
Disadvantages
Expensive to install first day
Not always available
Expensive to install first day
Not always available
Expensive to install first day
Expensive to install first day
Not always available
Equipment can be damaged in storms
Requires a lot of land
Expensive to install first day
Conservation of energy
The principle of conservation of energy states that energy cannot be created or
destroyed, but can only be converted from one form to another.
Energy Conversions
Appliance
Energy Conversion
Electric heater
Electricity to Heat
Speaker
Electricity to Sound
Light-bulb
Electricity to Light
The most useful form of energy is electrical energy. This is because it can be changed into other forms easily, e.g.
electric to motor to move things, electric to heat, electric to sound, electric to light.
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Potential Energy and Kinetic Energy
Another way of understanding energy is to divide energy up into two separate categories: potential energy and kinetic
energy.
Potential energy is energy that is stored, i.e. the energy can do work if released.
Examples of potential energy are a stretched string, water at the top of a dam and chemical energy in a battery.
Kinetic energy is energy that is associated with movement, i.e. anything that is moving has kinetic energy.
Experiments
a. Chemical energy to electrical energy to heat energy
An electric circuit consisting of a battery connected to a light-bulb or heater.
Switch on the circuit and note the temperature rising using a thermometer.
b. Electrical energy to magnetic energy to kinetic energy
Use an electromagnet (a coil of wire wrapped around a nail, connected to a battery) to pick up some nails.
c. Light energy to electrical energy to kinetic energy
Connect a solar panel to an electric motor which turns when light shines on the solar panel
Be able to answer all questions from the textbook and the workbook.
10
Exam questions
1. [2006 OL]
Energy cannot be created or destroyed but it can be changed from one form to another e.g. chemical energy can be
converted into heat energy.
Describe an experiment you could carry out to show the conversion of chemical energy to heat energy.
Draw a labelled diagram of any equipment used.
2. [2008 OL]
The diagram shows a common light bulb.
Complete the table below by writing the letter B beside the
two main energy changes that take place when the bulb is in
use.
Electrical to light
Electrical to sound
Electrical to heat
Chemical to heat
Heat to light
3. [2006 OL]
Give an example from everyday life where electrical energy is converted to kinetic
energy.
4. [2009]
Give two useful energy conversions that occur when the drill shown in the diagram is
being used.
5. [2008]
Fill in the missing words in both sentences.
(i) The stretched rubber chord has ______________ energy.
(ii) If the stone is released it will have ____________ energy.
6. [2007]
When work is done energy is converted from one form to another.
Identify one energy conversion that occurred when a car brakes.
7.
[2008 OL]
In the table write the letter R beside two forms of renewable energy.
8.
[2009 OL]
In the table write the letter N beside two forms of non-renewable energy.
Coal
Oil
Solar
Tidal
9. [2007 OL] [2007]
Nuclear energy could be used to solve Ireland’s energy shortage.
Give one advantage and one disadvantage of using nuclear energy to generate electricity.
10. [2008]
The Pelamis, shown in the photograph, converts the energy of waves in seas into
electrical energy.
Give one advantage and one disadvantage of generating electrical power in this way.
11. [2009]
Give one advantage or one disadvantage of fitting solar panels to your home?
12. [2006]
Suggest two alternative sources of energy (instead of fossil fuels) for the generation
of electricity in Ireland.
13. [2008]
(i) Name the energy from the sun that the solar panel changes into electricity.
(ii) The electrical energy is then changed into a form of energy that can be stored in a
battery Name the form of energy that can be stored in a battery.
(iii) In winter it may be dark when the pupils are going to or coming from school.
Give two energy conversions that occur to produce the flashes of light warning
motorists approaching the school on dark mornings.
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Oil
Wind
Solar
Coal
Wave
14. [2007]
The driver of a moving car applied the brakes.
The brakes produced an average stopping force of 8 kN (8000 N) and the car stopped having travelled 20 m after
the brakes were applied.
Calculate the work done in stopping the car.
15. [2006]
A girl of mass 60 kg (weight 600 N) climbed a 6 m high stairs in 15 seconds.
Calculate the work she did and the average power she developed while climbing the
stairs.
Energy Questions
1. Define the term ‘work’.
2. What are the units of work?
3. Define the term ‘energy’.
4. What are the units of energy?
5. Define the term ‘power’.
6. What are the units of power?
7. A force of 20 N was used to pull a sofa 3 metres across a room. How much work was done?
8. If the time taken in the previous question was 10 seconds, calculate the average power.
9. A weight-lifter lifted a weight of 1000 N a distance of 1.5 metres. How much work was done?
10. If the time taken in the previous question was 2 seconds, calculate the average power.
11. State the principle of conservation of energy.
12. What is meant by non-renewable energy?
13. Name a source of non-renewable energy?
14. What type of energy generates lightning?
15. State the principle of conservation of energy.
16. Write down two useful changes that occur when a hairdryer is in use.
17. What is nuclear energy?
18. State one advantage and one disadvantage of nuclear energy.
19. Why is electricity a convenient form of energy?
20. What is kinetic energy?
21. Give an example of electrical energy being converted to kinetic energy.
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22. Name one renewable energy source that can be used in Ireland.
23. Why is this source considered to be renewable?
24. Give two ways of increasing the energy efficiency of a house.
25. Draw a diagram of an experiment to demonstrate electrical energy being converted to magnetic energy and in turn
to kinetic energy.
26. Describe how to make a electromagnet.
27. Give two ways of increasing the strength of an electromagnet.
28. Complete the table.
Energy Conversion
Kinetic to Heat
Example
Rubbing your hand along a desk
Chemical to Heat
Potential to Sound
Light to Electric
29.
instrument
List two Energy conversions
Electric drill
Solar panel
Hair dryer
.
13
Physics: 9. Sound
Syllabus
OP40 Show that sound is a form of energy, and understand that sound is produced by vibrations
OP41 Show that sound transmission requires a medium and that echoes are reflected sound
OP42 Understand that the ear detects sound vibrations and that exposure to very loud sounds can cause damage to
hearing
OP43
Recall that the speed of sound is less than the speed of light
OP44
Explain the time lag between seeing and hearing the same event
Student Notes
Sound is a form of energy
To show that sound is a form of energy you must be able to show that it can do work (because energy is the ability to
do work). Work is done when an object is being moved. So we need to show that sound can move something.
Demonstration
Hang a balloon in front of a speaker; note that when the speaker is turned on the balloon moves.
Sound is produced by vibrations
Demonstration
Feel the speaker vibrate by putting your hand on it. Notice that as the sound gets louder the vibrations get bigger.
Sound requires a medium
Demonstration
Notice that you can see and hear the bell ringing before the vacuum pump is
switched on.
After pumping the air out you can still see the bell ringing but can no longer hear
it.
Echoes are reflected sound
Echoes occur when sound reflects from a surface back into your ears.
The ear detects sound vibrations
There are tiny hairs in your ear which vibrate when they detect sound and this then gets converted to electrical signals
which travel to the brain.
Exposure to very loud sounds can cause damage to hearing
This is why people who work with loud machinery need to wear ear protectors.
The speed of sound is less than the speed of light
The speed of sound is about 340 m/s while the speed of light is about one million times faster. This is why when
something far away makes a sound we can see it before we hear it, e.g. in an electrical storm we see the lightning
before we hear the thunder.
Ultrasound is a high-pitched sound beyond the range of the human ear
Maths problems: Speed = Distance ÷ Time
Note that if we are dealing with echoes from a wall, the distance the sound travels will be twice the distance between
the source of the sound and the wall.
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Exam Questions
1. [2007 OL][2009 OL]
A student set up the following experiment to investigate how sound travels
through air.
An electric bell was placed inside a bell-jar as shown in the diagram.
The bell rang and it could be heard clearly.
When the pump was switched on it started to pump the air out of the bell-jar and a
vacuum was created.
At that stage the bell could no longer be heard but it could still be seen ringing.
(i) What conclusion could be drawn from this investigation?
(ii) When the air was pumped out, the bell could still be seen even though it could not
be heard. What difference between light and sound does this show?
(iii) During an electric storm lightning is usually seen before thunder is heard.
What does this tell us about light and sound?
2. [2007]
Describe, using a labelled diagram in the box, an investigation you could carry out to show that sound requires a
medium in which to travel.
3. [2007][2008 OL]
The picture shows a flash of lightning.
(i) Which is detected first, the flash of lightning or the clap of thunder?
(ii) What does this tell us about the speed of light?
4. [2006] [2009]
How are echoes produced?
5. [2009 OL]
(i) The soldier in the diagram has safety goggles on his hat.
Give one reason why safety goggles should be used in the laboratory.
(ii) The sign on the right is found displayed at shooting ranges and in many
factories. What instruction does this sign give?
(iii) Why is it important to obey the instruction given by this sign?
Other Test Questions
1. How is sound produced?
2. Draw a labelled diagram of an apparatus used to show that sound is a form of energy.
3. Why is the moon sometimes referred to as “the silent planet”?
4. Draw a diagram and write a brief note to demonstrate that sound is caused by vibrations.
5. Draw a diagram and write a brief note to demonstrate that sound cannot travel through a vacuum.
6. What is ultrasound?
7. What is the speed of sound in air?
8. How are echoes produced?
9. Give two differences between sound and light waves.
10. Give two applications of reflected sound.
15
11. In a thunder and lightning storm, why do we see the lightning before we hear the thunder?
12. If the time-lag between seeing lightning and hearing thunder is 5 seconds, how far away is the storm?
13. When a girl was a certain distance from a high cliff she shouted loudly. One and a half seconds later the echo
returned from the cliff. How far was the girl from the cliff? (take the speed of sound to be 340 m/s).
14. A guitar string is plucked. The sound is heard. It seems simple, but there are a few stages in between. Can you put
the following stages in the correct order?
vibrating eardrum, brain, vibrating source, vibrating air, nerve
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Physics: 10. Light
OP33
OP34
OP35
Syllabus
Understand that light is a form of energy and that it can be converted to other forms
Show that light travels in straight lines and explain how shadows are formed.
Understand that luminous objects are a source of light while non-luminous objects are seen as a result of light
reflected from them.
OP36
Recall that white light is made up of different colours which can be separated by dispersion.
OP37
Produce a spectrum of white light using appropriate apparatus, and list the colours of the spectrum.
OP38
Investigate the reflection of light by plane mirrors, and illustrate this using ray diagrams.
Demonstrate and explain the operation of a simple periscope.
OP39
(all higher level)
Show the refraction of light as it passes from: air to glass, air to water, glass to air, water to air.
Show refraction of light through a lens.
Demonstrate the operation of a magnifying glass.
Student
Notes
Light is a form of energy and it can be converted to other forms
To show that light is a form of energy you must be able to show that it can do work
(because energy is the ability to do work). Work is done when an object is being moved.
So we need to show that light can move something.
Demonstration
Us a solar panel connected to a motor; when light shines on the solar panel the light
energy gets converted to electrical energy and this then gets converted to kinetic energy
in the motor (which turns).
Light travels in straight lines
Demonstration
Notice that you can only see light from the lamp when the holes in the card are
lined up (use a piece of cord to line them up).
How shadows are formed
Shadows are formed when light coming from a source is blocked. The
shadow is then similar in outline to the object blocking the light.
Demonstration:
Place your fingers between a candle and a screen and notice that as you bring your finger closer to
the candle more light gets blocked out and the shadow gets bigger.
Reflection is the bouncing of light from a surface
We can see objects because some of the light which leaves the objects hits our eyes.
Luminous objects are a source of light while non-luminous objects are seen as a result of light reflected from them.
Examples of luminous objects: the sun, a light-bulb, a candle.
Examples of non-luminous objects: everything else (not emitting their own light)
To investigate the reflection of light by plane mirrors
Demonstration
Use a ray box to shine a ray of light off a mirror.
Notice that it reflects back out at the same angle as it goes in.
How a periscope works
Some of the light coming from the card hits the first mirror, then gets reflected from this
onto the second mirror where it gets reflected again and travels out to the eye of the
observer.
17
Dispersion and Refraction
White light is made up of different colours which can be separated by dispersion
Dispersion is the breaking up of white light into its individual colours (called a spectrum)
The colours of the spectrum are Red, Orange, Yellow, Green, Blue, Indigo and Violet.
Make up a mnemonic to help yourself remember them e.g. Rover Often Yelps Grating Burglars Into Vegetables ??
To produce a spectrum of white light
Use a light bulb, a prism and a screen.
Turn the prism slowly until a spectrum is formed on the screen.
Note that red gets bent the least and violet gets bent the most, so X is red and Y
is violet.
Refraction is the bending of light as it passes from one medium to another
To demonstrate refraction
Shine a ray of light into a glass block and notice that it bends on the way in and also on the way
out.
Show refraction of light through a lens
A lens is a curved piece of glass used to bend (refract) light inwards or outwards.
To
demonstrate the operation of a magnifying glass
A magnifying glass refracts light to give a magnified image of the object.
Applications of refraction
You only need to know a couple of these:
Lenses, spectacles, magnifying glass, microscope, binoculars, telescopes, camera
lenses, prisms, projectors, endoscope, periscope etc.
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Exam questions
1. [2008 OL]
The diagram shows a ray of light striking a plane mirror.
(i) Complete the path taken by the ray in the diagram.
(ii) Name the property of light shown.
2. [2008]
The photograph shows a wader i.e. a bird that feeds in shallow water.
(i) Is the image of the bird produced by reflection or by refraction?
(ii) Give a reason for your answer.
3. [2006 OL]
The equipment shown in the diagram was set up and used in an experiment on
light.
(i) What would the eye on the right see if the middle card was moved slightly?
(ii) What does this experiment tell us about light?
4. [2007 OL]
Describe, with the help of a labelled diagram, how you could carry out an experiment to show that light travels in
straight lines.
Use the following headings: Equipment: Result: Labelled diagram
5. [2007 OL]
The diagram shows a ray of light shining onto a plane mirror in a periscope.
Complete the path taken by the ray in the diagram.
6. [2006]
A pupil made a simple periscope using two plane (flat)
mirrors.
The mirrors were arranged as shown in the diagram. The pupil
looked through the periscope at the word ‘Science’ written on
a card pinned to the laboratory wall.
Did the pupil see first image or the second image when she
looked through the periscope?
Give a reason for your answer.
7. [2006]
Why is the word Ambulance painted in reverse on the front of many ambulances?
8. [2008 OL]
The equipment shown in the diagram was set up and used in an experiment on light.
(i) Name the piece of equipment labelled A.
(ii) Name the colour labelled B.
9. [2008]
The photograph shows narrow beams of light (rays) passing through a lens-shaped
piece of transparent material. Parallel rays of light enter the material from the left
and when they leave the material they converge and pass through a common point,
before moving apart.
Give a use for a lens having this effect on light.
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10. [2008]
The diagram shows a ray of white light entering a triangular glass prism. The
light passes through the prism and emerges as a band of coloured light.
What does this experiment show about the composition of white light?
(i) What is this separation of white light into different colours called?
(ii) What name is given to the band of coloured light produced?
(iii) State the colour of the light labelled X and the colour of the light labelled Y at
the extreme ends of the band of light illustrated in the diagram.
11. [2008 OL]
The picture shows a flash of lightning.
(i) Which is detected first, the flash of lightning or the clap of thunder?
(ii) What does this tell us about the speed of light?
12. [2007]
Thunder and lightning occur during electric storms.
Explain why we see the lightning before we hear the thunder.
13. [2006][2007]
What is refraction of light?
14. [2007]
Give an everyday example of an effect caused by refraction.
15. [2007]
Name another way in which the direction of a light ray can be changed apart from refraction.
16. [2007]
Give an application of this bending of light.
17. [2007]
A glass block like the one shown in the diagram was used in an experiment in which a
narrow beam (ray) of light was shone through it. The light passed from air to glass, on
entry, and glass to air, on exit.
The path of this light ray is shown in the second diagram.
The light ray from A bends both on entering and on leaving the glass block.
Pick, from ‘rays’ P, Q, R or S the path taken by the light ray leaving the glass.
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General Questions
1. Why is lightning seen before the thunder is heard?
2. Describe briefly how you would show the conversion of light energy to electrical energy to kinetic energy.
3. Draw a diagram and write a brief note to demonstrate that light is a form of energy.
4. What is meant by the reflection of light?
5. What is meant by a luminous object?
6. Give an example of a luminous object.
7. Give two observations that suggest that light travels in straight lines.
8. How would you demonstrate that light travels in straight lines?
9. Show using a diagram how a periscope works. Include rays of light and make sure to put arrows on all rays. It
might help to turn this page sideways for the diagram.
10. Explain, using a diagram, how a shadow of a person is formed on a sunny day.
11. Describe how you would investigate the reflection of light from a plane mirror?
What results would you expect to notice?
12. Draw a diagram to show how light is reflected from a plane mirror.
13. Describe with the aid of diagram how a periscope works.
14. What is refraction?
15. What is the name given to the change in direction of light as it enters a prism?
16. Describe, with the aid of a diagram, an experiment to show the refraction of light as it passes through a lens.
17. Draw diagrams to show how(i) a Concave Lens, and (ii) a Convex Lens works
18. Explain, with the aid of a diagram, how a magnifying glass works.
19. What is the name given to the spreading out of sunlight into a band of colour?
20. Describe how you would investigate the dispersion of white light through a prism.
21. What is the name given to the band of colour itself?
22. How would you demonstrate dispersion?
Higher Order Questions
Why do rainbows often appear after a heavy shower of rain?
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