Lenses

Figure 1 shows a ray of light incident on a mirror.

Draw the reflected ray on Figure 1.

On Figure 1, label the angle of incidence with the letter i and the angle of reflection with the letter r.

A lens has a focal length of 17 cm.

Calculate the power of the lens in dioptres.

Use the equation

power =_........ dioptres

Which of these is the best reason for explaining why a leaf appears green in daylight?

Describe how the power of a lens is related to its focal length and the shape of the lens.

Give one example of a virtual image that a lens could produce.

Give one example of a real image that a lens could produce.

A student investigates what happens when a ray of light shines into a semicircular block made of transparent plastic.

The ray meets the straight edge at an angle of 20°, as shown in Figure 13.

The student gradually increases the angle at the straight edge from 20° to 50° and observes what happens to the ray of light.

The critical angle for the transparent plastic is 38°.

Describe what you would expect to happen to the ray of light as the angle at the straight edge increases from 20° to 50°.

You may add to the diagram in Figure 13 to help your answer.

The asteroid Ceres orbits the Sun between Mars and Jupiter.

During its orbit, Ceres receives electromagnetic radiation from the Sun.

The average temperature of Ceres is constant.

Explain why the average temperature of Ceres remains constant.

A flag has three colours in daylight.

The flag is taken into a dark room.

Figure 3 shows the flag when a torch shines white light on to the flag.

Figure 4 shows the same flag when the torch is covered with a coloured filter.

State the colour of the filter that has covered the torch.

A student uses a converging lens to produce an image of a tree on a screen.

The image of the tree on the screen is shown in Figure 5.

The student is asked to describe the image of the tree.

The student’s descriptions are shown in the table.

The first description is correct, the image is upside down.

Complete the table by adding the correct descriptions of the image.

A student uses a ray box to investigate two lenses, P and Q.

Figure 6 shows the student’s drawings of rays of light before and after passing through the lenses.

Complete the following sentences.

The focal length of lens P is_........ than the focal length of lens Q.

The power of lens P is_........ than the power of lens Q.

Figure 7 shows light reflecting from two mirrors in a bathroom.

Mirror R has a dry surface.

Mirror S has lots of small drops of water on the surface.

A person looks into each mirror.

Explain the difference between the image seen in mirror R and the image seen in mirror S.

The law of reflection of light applies to reflections from

A student uses a mirror to demonstrate that the angle of incidence is equal to the angle of reflection.

Figure 8 shows the apparatus the student uses.

Describe the procedure the student should use with the ray and mirror in the position shown in Figure 8.

You should include any extra equipment needed.

You may add to Figure 8 to help your answer.

Figure 9 shows a ray of light from a ray box passing through a semi-circular glass block.

A student uses the apparatus in Figure 9 to determine the critical angle for glass.

State why the ray of light does not change direction as it enters the glass block at X.

Describe how the critical angle for glass can be determined using the apparatus shown in Figure 9.

Figure 10 shows a ray diagram of the virtual image produced by a diverging lens.

State what is meant by the term virtual image.

Figure 3 shows a ray of light striking a mirror.

The angle of incidence is 30˚ and the ray of light is reflected.

The angle of reflection is the angle between

Figure 4 shows two lenses, P and Q, arranged to form a simple telescope.

State one use for a telescope.

Which of these describes the lenses?

The focal length of lens Q is 0.14 m.

Calculate the power of the lens.

Use the equation

power of lens =_........ dioptre

A student is in a laboratory that has windows.

The student is given a converging lens, and a sheet of paper.

Describe how the student can produce an image of the window frame on the sheet of paper.

This question is about reflection and refraction of light.

Figure 4 shows a ray of light travelling to a plane mirror.

On Figure 4, draw the ray of light after it reflects off the mirror surface.

Figure 5 shows a ray of light in air travelling to a glass block.

On Figure 5, draw the ray of light after it refracts at the surface of the glass block.

Figure 6 shows a ray of light in water, travelling to the surface of the water.

The angle marked X is greater than the critical angle.

On Figure 6, draw the ray of light after it reaches the surface of the water.

A converging lens has a focal length of 40 cm.

Calculate the power of this lens in dioptres.

Use the equation

power of the lens =_........ dioptres

Which ray diagram shows total internal reflection at an air and glass boundary?

Figure 1 is a ray diagram for a converging lens when used as a magnifying glass.

Using information from Figure 1, determine the magnification of the virtual image.

Use the equation

Describe one way the magnification of the image could be increased.

Figure 2 shows a converging lens used to produce a real image on a screen.

The apparatus is used to find the focal length, f, of the lens.

The screen is moved to give a clear image of the object.

The distance from the object to the lens, a = 20 cm.

The distance from the image to the lens, b = 40 cm.

Calculate the focal length, f, of the lens.

Use the equation

This question is about light.

White light includes all the colours in the visible spectrum.

A beam of white light is the only light that shines on a book. The book appears green. A red filter is placed between the source of white light and the book.

What colour does the book appear now?

Figure 8 shows a shiny metal ball.

A clear image of a building can be seen on the surface of the ball.

This clear image is an example of

Explain why the surface of the metal ball gives a clear image. You may draw diagrams to help with your answer.

Figure 9a and Figure 9b show rays of light before and after passing through different lenses.

State one similarity and one difference in the way the rays of light pass through the lenses.

Figure 10 shows two glass lenses P and Q.

State how the power of P is different from the power of Q.

*(d) Figure 11a shows refraction of light at a boundary between glass and air. Figure 11b shows total internal reflection of light at a boundary between glass

Use Figure 11a and Figure 11b to explain refraction and total internal reflection.

You may add to Figure 11a and Figure 11b to help with your answer.

Figure 4 shows two light rays hitting a glass lens.

On Figure 4, draw the two light rays after they leave this lens.

Figure 4

Figure 5 shows two light rays hitting a different glass lens.

On Figure 5, draw the two light rays after they leave this lens.

A lens has a focal length of 25 cm.

Calculate the power of the lens.

Use the equation

power of the lens =_........ dioptres

Figure 6 shows two solid metal balls, P and Q.

P and Q are made from the same metal and have the same radius.

P is painted black and Q is painted white.

Each ball is heated to a different temperature.

The balls then cool in the same room.

The graph in Figure 7 shows how the temperature of each ball changes with time.

Use the graph in Figure 7 to determine the time when P and Q were at the same temperature.

Show your working on the graph.

Which of these temperatures is most likely to be room temperature, as shown by the graph in Figure 7?

Explain why the curve for P is different from the curve of Q. Use information from Figure 6 and Figure 7 to help your answer.

Which lens is a converging lens with the greatest power?

The equation that relates the power of a lens to the focal length of the lens is

The power of a lens is 5 dioptres.

Use the equation to calculate the focal length of the lens in cm.

Figure 3 shows a semicircular glass block.

Figure 3

Describe how a student could use the semicircular glass block and other apparatus to determine the critical angle for a glass‑air boundary.

You should add to the diagram in Figure 3 to help with your answer.

A long time ago, scientists believed that the Earth was at the centre of the Solar System.

Evidence has since proved that the Sun is at the centre of the Solar System.

State one other idea about the Solar System that has changed over time.

Figure 4 shows data for some of the planets of the Solar System.

distance from the Sun in millions of km

Figure 4

Ceres is an asteroid that orbits the Sun between Mars and Jupiter. It takes Ceres 4.6 Earth years to make one orbit of the Sun.

Use the graph to estimate the distance of Ceres from the Sun.

Show your working.

distance of Ceres from the Sun =_........ millions of km

Figure 12 is a diagram showing a lens, with some light rays passing through it.

This diagram shows a

Which length, labelled on Figure 12, shows the focal length of the lens?

Calculate the power of a lens of focal length 17 cm.

Use the equation

Give the answer to 2 significant figures.

power =_........ dioptres

*(c) More than two thousand years ago the Earth was believed to be at the centre of the universe as shown in Figure 13.

The planets, the Moon and the Sun were believed to be in orbit around the Earth.

In 1543 Nicolaus Copernicus proposed that the Earth was a planet, and that the Earth and the other planets orbit around the Sun. This model is shown in Figure 14.

Discuss how evidence has changed our views of the universe.