1.
(i)
(ii)
(iii)
Exam questions: Refraction
[2005 OL]
What is meant by the reflection of light?
State the laws of reflection of light.
Describe an experiment to demonstrate one of the laws of reflection of light.
2.
[2010 OL]
Which of these scientists is associated with the law of refraction of light?
Rutherford Snell Joule Einstein
3.
[2008][2006][2002 OL][2004 OL][2005 OL][2009 OL]
What is meant by refraction of light?
4.
[2008]
State Snell’s law of refraction.
5.
[2002][2002 OL]
State the laws of refraction of light.
6.
[2004 OL]
What is meant by the refractive index of a material?
7. [2008]
(i) Light is refracted as it enters the cornea from air as shown in the diagram.
Calculate the refractive index of the cornea.
(ii) Draw a diagram to show the path of a ray of light as it passes from water of refractive index 1.33 into the
cornea.
8.
(i)
(ii)
(iii)
[2005 OL]
What special name is given to the angle of incidence i, when the effect shown in the diagram occurs?
In the diagram the value of the angle i is 41.80. Calculate a value for the refractive index of the glass.
Draw a diagram to show what happens to the ray of light when the angle of incidence i is increased to 450.
9.
[2003OL]
Explain, with the aid of a labelled diagram (i) critical angle, (ii) total internal reflection
10. [2004 OL]
When will total internal reflection occur?
11. [2004 OL]
Define the critical angle.
12. [2007]
The refractive index of a liquid is 1.35, what is the critical angle of the liquid?
13. [2003 OL]
The critical angle for the glass is 42o. Calculate the refractive index of the glass.
14. [2003]
Calculate the critical angle for diamond. The refractive index of diamond is 2.4.
15. [2010]
What is the critical angle of a sample of glass whose refractive index is 1.46?
16. [2003 OL]
(i) The diagram shows a 45o prism made of glass and a ray of light entering the prism from
air. Copy the diagram and show the path of the ray through the prism and back into the
air.
(ii) Explain why the ray follows the path that you have shown.
17. [2003 OL][2005 OL]
Give two uses of total internal reflection.
1.
2.
Exam Questions - Light
[2007]
Describe an experiment that demonstrates the wave nature of light.
[2005]
A student used a laser, as shown, to demonstrate that light is a wave motion.
Name the two phenomena that occur when the light passes through the pair of narrow slits.
3.
[2005]
A student used a laser, as shown, to demonstrate that light is a wave motion.
(i) A pattern is formed on the screen. Explain how the pattern is formed.
(ii) What is the effect on the pattern when the wavelength of the light is increased?
(iii) What is the effect on the pattern when the distance between the slits is increased?
4.
[2009 OL]
In an experiment a beam of monochromatic light passes through a diffraction grating and strikes a
screen.
(i) Describe what is observed on the screen.
(ii) Explain, with the aid of a diagram, how this phenomenon occurs.
(iii) What does this experiment tell us about the nature of light?
(iv) Name the property of light that can be determined in this experiment.
(v) What measurements must be taken to determine the property you named?
5.
[2008]
Why does diffraction not occur when light passes through a window?
6.
[2006]
A sound wave is diffracted as it passes through a doorway but a light wave is not. Explain why.
7.
[2009 OL]
What is a diffraction grating?
8.
[2009 OL]
Explain the term monochromatic light.
9.
[2002]
A diffraction grating has 200 lines per mm. What is the value of d in the diffraction grating formula nλ = d
sin θ ?
10. [2009]
Derive the diffraction grating formula
11. [2005]
Sound travels as longitudinal waves while light travels as transverse waves.
Explain the difference between longitudinal and transverse waves.
12. [2004]
What is meant by polarisation of waves?
13. [2003]
Which wave phenomenon can be used to distinguish between transverse waves and longitudinal waves?
14. [2005]
Describe an experiment to demonstrate that light waves are transverse waves.
15. [2003 OL][2010 OL]
Give one difference between light waves and sound waves.
16. [2007 OL][2009][2010 OL]
What is meant by the term dispersion?
1.
Exam Questions - Pressure
[2010 OL]
A concrete mixer delivered 50 m3 of concrete to a building site, what was the mass of the concrete
delivered?
(Density of concrete = 2400 kg m−3)
2.
[2006][2002 OL][2005 OL][2007 OL][2009 OL]
Define pressure.
3.
[2002 OL][2005 OL]
Give the unit of pressure.
4.
[2006]
Is pressure a vector quantity or a scalar quantity? Justify your answer.
5.
[2002 OL][2005 OL]
Name an instrument used to measure pressure.
6.
[2002 OL]
The wind exerts a horizontal force of 1000 N on a wall of area 20 m2. Calculate the pressure at the wall.
7.
[2008 OL]
A solid block in the shape of a cube of length 120 cm rests on a table. The weight of the block is
25 N. Calculate the pressure it exerts on the table.
8.
[2005]
A container contains 5.0 kg of water. If the area of the base of the container is 0.5 m2.
Calculate the pressure at the base of the container due to the water.
P = F/A = [ (5.0)(9.8)/(0.5)]

P = 98 Pa
Mathematical pressure
9. [2005 OL]
(i) The African elephant is the largest land animal.
An elephant weighs 40 000 N and is standing on all four feet each of area 0.2 m2.
Calculate the pressure exerted on the ground by the elephant.
(ii) Why would the pressure on the ground be greater if the elephant stood up on just two feet?
10. [2008]
The head of a thumbtack has an area of 500 mm2. Its point has an area of 0.3 mm2. The pressure exerted at
the head of the thumbtack is 12 Pa. What is the pressure exerted at the point of the thumbtack?
Atmospheric Pressure
11. [2005 OL][2007 OL]
Describe an experiment to show that the atmosphere exerts pressure.
12. [2002 OL]
When air is removed from the metal container shown in the diagram, it collapses. Explain why.
13. [2005 OL]
The earth is covered with a layer of air called the atmosphere.
What holds this layer of air close to the earth?
14. [2005 OL]
The type of weather we get depends on the atmospheric pressure.
Describe the kind of weather we get when the atmospheric pressure is high.
Exam Questions - moments
1. [2003 OL][2006 OL]
Define the moment of a force.
2. [2006]
Why is it easier to turn a nut using a longer spanner than a shorter one?
3. [2003 OL]
Explain why the handle on a door is on the opposite side to the hinges of the door.
4. [2006 OL]
A crane is an example of a lever. Give another example of a lever.
5. [2010]
What are the two conditions for the equilibrium of a set of co-planar forces?
6. [2003]
The diagram shows forces of 5 N applied to a water tap.
Calculate the moment of the couple (torque) on the tap.
7. [2003 OL]
(i) A metre stick is suspended by a thread at the 20 cm mark as shown in the
diagram. The weight W of the metre stick acts through the 50 cm mark. A
weight of 2 N is placed at the 15 cm mark.
Calculate the moment of the 2 N weight about the 20 cm mark.
(ii) What is the moment of W about the 20 cm mark?
(iii) If the metre stick is in equilibrium, find the value of W.
8. [2009 OL]
A man opens a door by applying a force of 5 N to the door.
The distance from the point of application of the force to the fulcrum is 120 cm.
Calculate the moment of the applied force. (M = Fd)
9. [2006 OL]
(i) The diagram shows a crane in equilibrium.
Give one condition that is necessary for the crane to be in
equilibrium.
(ii) What is the moment of the 9000 N concrete slab about the axis of
the crane?
(iii) Calculate the value of the load marked X.
Exam solutions: Refraction
1.
(i) Reflection is the bouncing of light from a surface.
(ii) The incident ray, the normal at the point of incidence and the reflected ray all lie on the same
plane.
The angle of incidence is equal to the angle of reflection (i = r).
(iii) Apparatus: raybox, mirror.
Procedure: mark the position of the rays and measure the angles i and r.
Observation/conclusion: i = r.
2. Snell
3. Refraction of light is the bending of light as it passes from one medium to another (of different
refractive index).
4. The ratio of the sin of the sin of the angle of incidence to the sin of the angle of refraction is a
constant.
5. The incident ray, the normal and the refracted ray all lie on the same plane.
The ratio of the sin of the sin of the angle of incidence to the sin of the angle of refraction is a
constant.
6. n = sin i/ sin r, where i is the angle of incidence and r is the angle of refraction.
sin 𝑖
7. sin 𝑟 = ŋ
(i)
 n = sin 37/sin 27  n = 1.33
(ii) Both media have the same refractive index so there is no bending of light so draw a straight line
passing from one medium to the other without bending.
8.
(i) It is called the critical angle.
(ii) n= 1/ sin C 
n = 1/sin 41.80  n = 1/0.67  n = 1.5.
(iii) See diagram.
9.
(i) The critical angle corresponds to the angle of incidence in the denser of two
media which causes the angle of refraction to be 900.
(ii) Total internal reflection occurs when the angle of incidence in the denser of
the two media is greater than the critical angle and light is reflected back into
the denser medium.
10. When the angle of incidence is greater than the critical angle.
11. The critical angle corresponds to the angle of incidence in the denser of two
media which causes the angle of refraction to be 900.
12. ng =1/ sin c  c = 47.80
13. n = 1/sin C  n = 1/ sin 42
 n = 1.5
14. n = 1/ sin c  c = 24.6 0.
15. n = 1/sin c  c = 43.2o
16.
(i) See diagram
(ii) Because total internal reflection occurs twice while inside the prism.
17. Fibre optics, endoscopes, reflective road signs, telecommunications, binoculars,
periscope.
Exam Solutions – Light
1. Shine a laser through a diffraction grating; an interference pattern will be produced on a screen,
caused by interference of the light waves
2. Diffraction and Interference
3.
(i) The slits act as sources of two coherent waves which overlap to give areas of constructive
interference (bright lines) and destructive interference (dark lines).
(ii) The pattern becomes more spread out.
(iii) The pattern becomes less spread out.
4.
(i) A series of bright dots.
(ii) The light waves pass through the diffraction grating and spread out on the
other side after passing through the slit.
Constructive and destructive interference occurs and fringes are formed on the
screen as shown in the diagram.
(iii) Light is a wave.
(iv) The wavelength of light can be measured.
(v) The distance between bright dots, distance from the screen to grating.
5. The window is too wide (relative to wavelength of light).
6. Diffraction only occurs when the width of the gap is approximately equal to
the wavelength of the wave. This is the case for a sound wave but the wavelength of a light-wave
is very small compared to the size of a doorway.
7. A diffraction grating consists of a piece of transparent material on which a very large number of
opaque (black) parallel lines are engraved.
8. Monochromatic light is light of one wavelength only.
9. d = 1/200000 = 5 × 10-6 m.
10.
From the diagram we can see that
(i)
For constructive interference to occur, the extra path length
that the top ray travels must be an integer number of wavelengths
(n)
{Eqn (1)}
(ii)
Using trigonometry, this extra path length is equal to d sin
, where d is the slit width
{Eqn (2)}
Equating (1) and (2) gives us n = d Sin 
11. Longitudinal waves: the direction of the vibrations is parallel to the direction of propagation of
the wave.
Transverse wave: the direction of the vibrations is perpendicular to the direction of the wave.
12. A polarized wave is one which vibrates in one plane only.
13. Polarisation
14.
 Light source and two pieces of polaroid as shown.
 Rotate one polaroid relative to the other and note that the light intensity
transmitted through both polaroids increases and decreases
 Conclusion: Only transverse waves can be polarised, so light is a transverse
wave.
15.
 Light waves are transverse; sound waves are longitudinal.
 Light waves can be polarised; sound waves cannot be polarised.
 Light waves travel through a vacuum; sound waves cannot travel through a vacuum.
16. Dispersion is the breaking up of white light into its constituent colours
Exam Solutions - Pressure
1. m = 2400 × 50 = 120000 kg
2. Pressure = Force ÷ area.
3. The unit of pressure is the pascal.
4. It is a scalar because it has no direction.
5. The barometer.
Mathematical pressure
6. P = F/A = 1000/20 = 50 Pascals.
7. P = F/A

P = 25 ÷ (1.2)2 
8. P = F/A = [ (5.0)(9.8)/(0.5)]
9.
(i) P = F/A

P = 40 000/0.8
(ii) The area would be smaller.

P = 17.4 pa
P = 98 Pa

P = 5,000 Pa.
10. (at head:) F = P × A
 F = 12(500 × 10-6)  F = 6.0 × 10-3 N
Note that the force is constant throughout.
(at point:) P = F/A = (6.0 × 10-3) / 0.3 × 10-6) = 2.0 × 104 Pa
Atmospheric Pressure
11. Apparatus: glass of water and cardboard.
Procedure: place cardboard over glass and invert.
Observation/conclusion: water remains in glass.
12. The pressure outside (due to atmospheric pressure) is greater than the pressure inside.
13. Gravity.
14. Good weather, dry, clear skies, little wind, settled.
Exam Solutions – Moments
1.
2.
3.
4.
5.
The moment of a force = the force × perpendicular distance between the force and the fulcrum.
The distance from the fulcrum is greater therefore there is a greater turning effect.
In order to maximise the distance between the force and the fulcrum.
Crowbar / nailbar / nutcracker / wheelbarrow / tongs / door handle etc.
Forces up = forces down // (algebraic) sum of forces acting is zero
(Algebraic) sum of the moments (of the forces about any point) is zero
6. Moment = force × distance = 5 × .06 = 0.3 N m
7.
(i) M = F × d = 2 × 0.05 = 0.1N m
(ii) M = F × d = 0.3 W
(iii) 0.1 = 0.3W  W = 0.33 N
8. Moment = 5 × 1.2 = 6 N m
9.
(i) The clockwise moments must equal the anticlockwise moments.
(ii) Moment = F × distance = 9000 × 10 = 90000 N m.
(iii) 9000 × 10 = 30x

x = 3000 N.