Reflection
State the laws of reflection of light. [2005 OL][2011 OL][2012 OL][2014 OL]
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).
Describe the image that is formed in a concave mirror when an object is placed inside the focus.
[2003 OL] [2007 OL]
The image is virtual, magnified and upright.
A concave mirror can produce a real or a virtual image, depending on the position of the object.
Give one difference between a real image and a virtual image. [2004 OL]
A real image can be obtained on a screen; a virtual image cannot.
In a real image the light rays meet; in a virtual image they do not.
A real image is always inverted/ a virtual is erect, a real image is in front / a virtual image is behind.
Give two uses for a concave mirror. [2004 OL][2011 OL][2012 OL]
Torch, headlights, searchlight, dentist mirror, cosmetic mirror, solar furnace.
Concave mirrors, rather than convex mirrors, are used by dentists to examine teeth. Explain why. [2014]
They give a magnified image
Why is a convex mirror used, instead of a plane mirror, as a door mirror on a car? [2010]
A convex mirror offers a wider field of view
Refraction
What is meant by refraction of light? [2008] [2006][2009 OL][2005 OL][2002 OL][2014 OL]
Refraction is the bending of light as it goes from one medium to another.
State the laws of refraction of light. [2002][2003 OL][2011]
The incident ray, the refracted ray and the normal all lie in the same plane.
Sin i/ Sin r is a constant
State Snell’s law of refraction. [2008]
The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant.
What is meant by the refractive index of a material? [2004 OL]
n = sin i/ sin r, where i is the angle of incidence and r is the angle of refraction.
Define the term critical angle. [2004 OL][2003 OL][2011 OL]
The critical angle corresponds to the angle of incidence in the denser of two media which causes the angle of refraction to be 900.
Define the term total internal reflection. [2003 OL]
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.
Explain, with the aid of a diagram, how total internal reflection can occur. [2011 OL]
The angle of incidence greater than critical angle
Total internal reflection occurs
This is repeated all along the fibre
Give two uses of total internal reflection. [2003 OL][2005 OL]
Fibre optics, endoscopes, reflective road signs, telecommunications, binoculars, periscope.
Why is each fibre in an optical fibre cable coated with glass of lower refractive index? [2009]
Because total internal reflection can only occur for rays travelling from a denser to a rarer medium.
How is the escape of light from the sides of an optical fibre prevented? [2004 OL]
Total internal reflection occurs due to an outer cladding of lower refractive index.
An optical fibre has an outer less dense layer of glass. What is the role of this layer of glass? [2004][2009]
Total internal reflection will only occur if the outer medium is of lower density.
It also prevents damage to the surface of the core.
Give an expression for the critical angle of the glass in an optical fibre in terms of the speed of light in the glass and the speed of light in air. [2014]
n = 1/Sin C
n = c air/c glass
sin C = c glass/c air
C = Sin–1(c glass/c air)
Give one use for optical fibres. [2004 OL]
Endoscope, telecommunications, binoculars.
Give two reasons why the telecommunications industry uses optical fibres instead of copper conductors to transmit signals. [2004][2011 OL]
Less interference, boosted less often, cheaper raw material, occupy less space, more information carried in the same space, flexible for inaccessible places, do not corrode, etc.
Name a material that is used in the manufacture of optical fibres. [2004 OL]
Glass / plastic / sand / silicon
Lenses
A diverging lens cannot be used as a magnifying glass. Explain why. [2006]
The image is always diminished
How does the eye bring objects at different distances into focus? [2002]
It can change the shape of the lens which in turn changes the focal length of the lens.
Give a common use for a convex lens. [2013 OL]
Magnification, (eye) glasses, binoculars, contact lenses, camera, etc.
1
,Velocity and acceleration
Define velocity [2009 OL][2008 OL][2004 OL][2002 OL]
Velocity is the rate of change of displacement with respect to time.
Explain the distinction between speed and velocity. [2014 OL]
velocity is speed in a given direction // velocity is a vector // sound is a scalar
Define acceleration [2008 OL][2004 OL][2002 OL]
Acceleration is the change in velocity with respect to time
Explain the term acceleration due to gravity, g. [2006 OL][2003 OL][2012]
It is the acceleration of an object which is in freefall due to the gravitational pull of the earth.
OR Acceleration caused by the earth
Why does the value of g, the acceleration due to gravity, vary at different locations on the surface on the earth? [2010]
Locations are at different distances from the earth’s centre / earth is not perfectly spherical / etc.
Why is the acceleration due to gravity on the moon less than the acceleration due to gravity on earth?
[2012 OL]
Because the mass of the moon is less than the mass of the earth
Suggest a reason why the module of the spacecraft when launched from the moon does not need a streamlined shape like those that are launched from earth. [2012 OL]
There is no atmosphere on the moon so no air resistance / drag / friction
Vectors
Give the difference between vector quantities and scalar quantities and give one example of each. [2014][2003][2013 OL]
A vector is a quantity which has magnitude and direction. Example: force, velocity, acceleration, etc
A scalar is a quantity which has magnitude only. Example: Time, mass, speed etc
Force is a vector quantity. Explain what this means. [2006 OL]
A vector is a quantity which has magnitude and direction.
Force, mass and momentum
Define the newton, the unit of force. [2008]
The newton is the force that gives a mass of 1 kg an acceleration of 1 m s-2.
Define Force [2004] [2008 OL][2006 OL][2013 OL][2014 OL]
A force is something which causes an acceleration.
Define Momentum [2004][2004 OL][2010 OL][2013 OL]
Momentum = mass × velocity
State The Principle of Conservation of Momentum.
[2002][2009 OL][2008 OL][2007 OL][2005 OL][2004 OL][2010 OL][2012 OL][2013][2013 OL]
In any interaction between two objects, the total momentum before the interaction is equal to the total momentum after the co llision, provided no external forces act.
State Newton’s first law of motion. [2011 OL]
A body will remain at rest or moving at a constant velocity unless acted on by an (external) force,
State Newton’s Second Law of Motion [2009][2004] [2003][2007 OL]
Force is proportional to the rate of change of momentum.
State Newton’s Third law of Motion. [2006]
When body A exerts a force on body B, B exerts a force equal in magnitude (and) opposite in direction to A.
Name two forces acting on a cheetah while it is running. [2004 OL]
Air resistance, gravity, friction
Why is the astronaut’s weight greater on earth than on the moon? [2006 OL]
Because acceleration due to gravity is greater on the earth (because the mass of the earth is greater than the mass of the moon).
The earth is surrounded by a layer of air, called its atmosphere.
Explain why the moon does not have an atmosphere. [2006 OL]
Because gravity is less on the moon.
A powerful rocket is required to leave the surface of the earth.
A less powerful rocket is required to leave the surface of the moon. Explain why. [2008 OL]
The force of gravity is less on moon so less force is needed to escape.
Using Newton’s first law of motion, explain what would happen to the passengers in a plane if they were not wearing seatbelts while the aircraft was landing. [2002 OL]
They would continue to move at the greater initial velocity and so would be ‘thrown’ forward.
Draw a diagram showing the forces acting on a car travelling on a road. [2011 OL]
Draw a diagram to show the forces acting on the ball when it is at
position A. [2006]
Weight (W) downwards; reaction (R) upwards; force to left (due
to friction or curled fingers)
2
, Use a diagram to show the forces acting on the skydiver and explain why he reaches a constant speed. [2003]
Weight acting down.
Air resistance / friction / buoyancy acting up.
Air resistance = weight, therefore resultant force = 0
Therefore acceleration = 0
Draw a diagram showing the forces acting on a rocket at lift-off. [2012 OL]
Weight acting down, thrust acting up.
What is friction? [2007][2009 OL][2006 OL][2002 OL][2011 OL]
Friction is a force that opposes the relative motion between two surfaces in contact.
A rocket is launched by expelling gas from its engines.
Use the principle of conservation of momentum to explain why a rocket rises. [2007 OL][2010 OL][2013 OL]
The gas moves down (with a momentum) causing the rocket to move up (in the opposite direction with an equal momentum).
A spacecraft is approaching a space station at a constant speed. The spacecraft must slow for it to lock onto the space station. In what direction should the gas be expelled? [2002]
Forward (toward the space station).
Explain how the principle of conservation of momentum is applied to changing the direction in which a spacecraft is travelling. [2002]
As the gas is expelled with a momentum in one direction the rocket moves in the other direction with an equal momentum.
Pressure
Define pressure. [2006][2009 OL][2007 OL][2005 OL][2002 OL][2013 OL]
Pressure is Force per unit Area.
Give the unit of pressure. [2002 OL][2005 OL][2014 OL]
The pascal
Name an instrument used to measure pressure. [2002 OL][2005 OL]
A barometer
Is pressure a vector quantity or a scalar quantity? Justify your answer. [2006]
It is a scalar quantity because it does not have a direction.
A balloon rises through the atmosphere while the temperature remains constant.
What will happen to the balloon as it continues to rise? [2007 OL]
It will expand.
When air is removed from a metal container it collapses. Explain why. [2002 OL]
The pressure outside (due to atmospheric pressure) is greater than the pressure inside.
The earth is covered with a layer of air called the atmosphere.
What holds this layer of air close to the earth? [2005 OL]
Gravity.
The type of weather we get depends on the atmospheric pressure.
Describe the kind of weather we get when the atmospheric pressure is high. [2005 OL]
Good weather, dry, clear skies, little wind, settled.
State Boyle’s law. [2014][2009][2006][2007 OL][2003 OL][2011 OL]
For a fixed mass of gas at constant temperature, the pressure is inversely proportional to the volume.
State Archimedes Principle. [2007][2014 OL]
When an object is immersed in a fluid, the upthrust it experiences is equal to the weight of the displaced fluid.
State the law of flotation. [2008]
For a floating object, the weight of the object equals the weight of the fluid displaced.
Gravity
State Newton’s Law of Gravitation. [2013][2010][2008] [2005] [2004][2008 OL][2003 OL][2014 OL]
Any two objects in the universe are attracted to each other with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between them.
Give two factors which affect the size of the gravitational force between two bodies. [2006 OL]
The mass of the objects and the distance between them.
What is the relationship between the acceleration due to gravity g and the distance from the centre of the earth? [2003]
g is proportional to 1/d2
The international space station (ISS) moves in a circular orbit around the equator at a height of 400 km.
What type of force is required to keep the ISS in orbit?
What is the direction of this force? [2008]
Gravity
Towards the centre of the orbit / inwards / towards the earth
An astronaut in the ISS appears weightless. Explain why. [2008][2013]
He is in a state of free-fall (the force of gravity cannot be felt).
Describe the variation in the weight of the astronauts as they travel to the moon. [2010]
Weight decreases as the astronaut moves away from the earth and gains (a lesser than normal) weight as she/he approaches the moon
Why is the acceleration due to gravity on the moon less than the acceleration due to gravity on the earth?
[2003 OL]
The earth has a greater mass than the moon.
The earth is covered with a layer of air called the atmosphere.
What holds this layer of air close to the earth? [2005 OL]
Gravity.
The earth is surrounded by a layer of air, called its atmosphere. Explain why the moon does not have an atmosphere. [2006 OL][2010]
Because gravity is less on the moon.
3
State the laws of reflection of light. [2005 OL][2011 OL][2012 OL][2014 OL]
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).
Describe the image that is formed in a concave mirror when an object is placed inside the focus.
[2003 OL] [2007 OL]
The image is virtual, magnified and upright.
A concave mirror can produce a real or a virtual image, depending on the position of the object.
Give one difference between a real image and a virtual image. [2004 OL]
A real image can be obtained on a screen; a virtual image cannot.
In a real image the light rays meet; in a virtual image they do not.
A real image is always inverted/ a virtual is erect, a real image is in front / a virtual image is behind.
Give two uses for a concave mirror. [2004 OL][2011 OL][2012 OL]
Torch, headlights, searchlight, dentist mirror, cosmetic mirror, solar furnace.
Concave mirrors, rather than convex mirrors, are used by dentists to examine teeth. Explain why. [2014]
They give a magnified image
Why is a convex mirror used, instead of a plane mirror, as a door mirror on a car? [2010]
A convex mirror offers a wider field of view
Refraction
What is meant by refraction of light? [2008] [2006][2009 OL][2005 OL][2002 OL][2014 OL]
Refraction is the bending of light as it goes from one medium to another.
State the laws of refraction of light. [2002][2003 OL][2011]
The incident ray, the refracted ray and the normal all lie in the same plane.
Sin i/ Sin r is a constant
State Snell’s law of refraction. [2008]
The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant.
What is meant by the refractive index of a material? [2004 OL]
n = sin i/ sin r, where i is the angle of incidence and r is the angle of refraction.
Define the term critical angle. [2004 OL][2003 OL][2011 OL]
The critical angle corresponds to the angle of incidence in the denser of two media which causes the angle of refraction to be 900.
Define the term total internal reflection. [2003 OL]
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.
Explain, with the aid of a diagram, how total internal reflection can occur. [2011 OL]
The angle of incidence greater than critical angle
Total internal reflection occurs
This is repeated all along the fibre
Give two uses of total internal reflection. [2003 OL][2005 OL]
Fibre optics, endoscopes, reflective road signs, telecommunications, binoculars, periscope.
Why is each fibre in an optical fibre cable coated with glass of lower refractive index? [2009]
Because total internal reflection can only occur for rays travelling from a denser to a rarer medium.
How is the escape of light from the sides of an optical fibre prevented? [2004 OL]
Total internal reflection occurs due to an outer cladding of lower refractive index.
An optical fibre has an outer less dense layer of glass. What is the role of this layer of glass? [2004][2009]
Total internal reflection will only occur if the outer medium is of lower density.
It also prevents damage to the surface of the core.
Give an expression for the critical angle of the glass in an optical fibre in terms of the speed of light in the glass and the speed of light in air. [2014]
n = 1/Sin C
n = c air/c glass
sin C = c glass/c air
C = Sin–1(c glass/c air)
Give one use for optical fibres. [2004 OL]
Endoscope, telecommunications, binoculars.
Give two reasons why the telecommunications industry uses optical fibres instead of copper conductors to transmit signals. [2004][2011 OL]
Less interference, boosted less often, cheaper raw material, occupy less space, more information carried in the same space, flexible for inaccessible places, do not corrode, etc.
Name a material that is used in the manufacture of optical fibres. [2004 OL]
Glass / plastic / sand / silicon
Lenses
A diverging lens cannot be used as a magnifying glass. Explain why. [2006]
The image is always diminished
How does the eye bring objects at different distances into focus? [2002]
It can change the shape of the lens which in turn changes the focal length of the lens.
Give a common use for a convex lens. [2013 OL]
Magnification, (eye) glasses, binoculars, contact lenses, camera, etc.
1
,Velocity and acceleration
Define velocity [2009 OL][2008 OL][2004 OL][2002 OL]
Velocity is the rate of change of displacement with respect to time.
Explain the distinction between speed and velocity. [2014 OL]
velocity is speed in a given direction // velocity is a vector // sound is a scalar
Define acceleration [2008 OL][2004 OL][2002 OL]
Acceleration is the change in velocity with respect to time
Explain the term acceleration due to gravity, g. [2006 OL][2003 OL][2012]
It is the acceleration of an object which is in freefall due to the gravitational pull of the earth.
OR Acceleration caused by the earth
Why does the value of g, the acceleration due to gravity, vary at different locations on the surface on the earth? [2010]
Locations are at different distances from the earth’s centre / earth is not perfectly spherical / etc.
Why is the acceleration due to gravity on the moon less than the acceleration due to gravity on earth?
[2012 OL]
Because the mass of the moon is less than the mass of the earth
Suggest a reason why the module of the spacecraft when launched from the moon does not need a streamlined shape like those that are launched from earth. [2012 OL]
There is no atmosphere on the moon so no air resistance / drag / friction
Vectors
Give the difference between vector quantities and scalar quantities and give one example of each. [2014][2003][2013 OL]
A vector is a quantity which has magnitude and direction. Example: force, velocity, acceleration, etc
A scalar is a quantity which has magnitude only. Example: Time, mass, speed etc
Force is a vector quantity. Explain what this means. [2006 OL]
A vector is a quantity which has magnitude and direction.
Force, mass and momentum
Define the newton, the unit of force. [2008]
The newton is the force that gives a mass of 1 kg an acceleration of 1 m s-2.
Define Force [2004] [2008 OL][2006 OL][2013 OL][2014 OL]
A force is something which causes an acceleration.
Define Momentum [2004][2004 OL][2010 OL][2013 OL]
Momentum = mass × velocity
State The Principle of Conservation of Momentum.
[2002][2009 OL][2008 OL][2007 OL][2005 OL][2004 OL][2010 OL][2012 OL][2013][2013 OL]
In any interaction between two objects, the total momentum before the interaction is equal to the total momentum after the co llision, provided no external forces act.
State Newton’s first law of motion. [2011 OL]
A body will remain at rest or moving at a constant velocity unless acted on by an (external) force,
State Newton’s Second Law of Motion [2009][2004] [2003][2007 OL]
Force is proportional to the rate of change of momentum.
State Newton’s Third law of Motion. [2006]
When body A exerts a force on body B, B exerts a force equal in magnitude (and) opposite in direction to A.
Name two forces acting on a cheetah while it is running. [2004 OL]
Air resistance, gravity, friction
Why is the astronaut’s weight greater on earth than on the moon? [2006 OL]
Because acceleration due to gravity is greater on the earth (because the mass of the earth is greater than the mass of the moon).
The earth is surrounded by a layer of air, called its atmosphere.
Explain why the moon does not have an atmosphere. [2006 OL]
Because gravity is less on the moon.
A powerful rocket is required to leave the surface of the earth.
A less powerful rocket is required to leave the surface of the moon. Explain why. [2008 OL]
The force of gravity is less on moon so less force is needed to escape.
Using Newton’s first law of motion, explain what would happen to the passengers in a plane if they were not wearing seatbelts while the aircraft was landing. [2002 OL]
They would continue to move at the greater initial velocity and so would be ‘thrown’ forward.
Draw a diagram showing the forces acting on a car travelling on a road. [2011 OL]
Draw a diagram to show the forces acting on the ball when it is at
position A. [2006]
Weight (W) downwards; reaction (R) upwards; force to left (due
to friction or curled fingers)
2
, Use a diagram to show the forces acting on the skydiver and explain why he reaches a constant speed. [2003]
Weight acting down.
Air resistance / friction / buoyancy acting up.
Air resistance = weight, therefore resultant force = 0
Therefore acceleration = 0
Draw a diagram showing the forces acting on a rocket at lift-off. [2012 OL]
Weight acting down, thrust acting up.
What is friction? [2007][2009 OL][2006 OL][2002 OL][2011 OL]
Friction is a force that opposes the relative motion between two surfaces in contact.
A rocket is launched by expelling gas from its engines.
Use the principle of conservation of momentum to explain why a rocket rises. [2007 OL][2010 OL][2013 OL]
The gas moves down (with a momentum) causing the rocket to move up (in the opposite direction with an equal momentum).
A spacecraft is approaching a space station at a constant speed. The spacecraft must slow for it to lock onto the space station. In what direction should the gas be expelled? [2002]
Forward (toward the space station).
Explain how the principle of conservation of momentum is applied to changing the direction in which a spacecraft is travelling. [2002]
As the gas is expelled with a momentum in one direction the rocket moves in the other direction with an equal momentum.
Pressure
Define pressure. [2006][2009 OL][2007 OL][2005 OL][2002 OL][2013 OL]
Pressure is Force per unit Area.
Give the unit of pressure. [2002 OL][2005 OL][2014 OL]
The pascal
Name an instrument used to measure pressure. [2002 OL][2005 OL]
A barometer
Is pressure a vector quantity or a scalar quantity? Justify your answer. [2006]
It is a scalar quantity because it does not have a direction.
A balloon rises through the atmosphere while the temperature remains constant.
What will happen to the balloon as it continues to rise? [2007 OL]
It will expand.
When air is removed from a metal container it collapses. Explain why. [2002 OL]
The pressure outside (due to atmospheric pressure) is greater than the pressure inside.
The earth is covered with a layer of air called the atmosphere.
What holds this layer of air close to the earth? [2005 OL]
Gravity.
The type of weather we get depends on the atmospheric pressure.
Describe the kind of weather we get when the atmospheric pressure is high. [2005 OL]
Good weather, dry, clear skies, little wind, settled.
State Boyle’s law. [2014][2009][2006][2007 OL][2003 OL][2011 OL]
For a fixed mass of gas at constant temperature, the pressure is inversely proportional to the volume.
State Archimedes Principle. [2007][2014 OL]
When an object is immersed in a fluid, the upthrust it experiences is equal to the weight of the displaced fluid.
State the law of flotation. [2008]
For a floating object, the weight of the object equals the weight of the fluid displaced.
Gravity
State Newton’s Law of Gravitation. [2013][2010][2008] [2005] [2004][2008 OL][2003 OL][2014 OL]
Any two objects in the universe are attracted to each other with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between them.
Give two factors which affect the size of the gravitational force between two bodies. [2006 OL]
The mass of the objects and the distance between them.
What is the relationship between the acceleration due to gravity g and the distance from the centre of the earth? [2003]
g is proportional to 1/d2
The international space station (ISS) moves in a circular orbit around the equator at a height of 400 km.
What type of force is required to keep the ISS in orbit?
What is the direction of this force? [2008]
Gravity
Towards the centre of the orbit / inwards / towards the earth
An astronaut in the ISS appears weightless. Explain why. [2008][2013]
He is in a state of free-fall (the force of gravity cannot be felt).
Describe the variation in the weight of the astronauts as they travel to the moon. [2010]
Weight decreases as the astronaut moves away from the earth and gains (a lesser than normal) weight as she/he approaches the moon
Why is the acceleration due to gravity on the moon less than the acceleration due to gravity on the earth?
[2003 OL]
The earth has a greater mass than the moon.
The earth is covered with a layer of air called the atmosphere.
What holds this layer of air close to the earth? [2005 OL]
Gravity.
The earth is surrounded by a layer of air, called its atmosphere. Explain why the moon does not have an atmosphere. [2006 OL][2010]
Because gravity is less on the moon.
3
