Visible light & colour

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?

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.

A student does an experiment to determine the critical angle for glass.

The student shines a ray of light into a semicircular glass block and measures the angles i and r, as shown in Figure 14.

The ray of light does not change direction when it enters the glass block at point X.

Which of these explains why the ray of light does not change direction when it enters the glass block at point X.

The student repeats the procedure for different values of angle i.

Figure 15 is a graph of the student’s results.

Describe how the student should use the graph in Figure 15 to determine the critical angle for glass.

Figure 16 shows two iron spheres, P and Q, near to a radiant heater. P is painted black and Q is painted white.

Each sphere is the same distance away from the heater.

The spheres have the same radius.

The heater is switched on and the spheres heat up.

The temperature of each sphere is monitored.

Explain why the temperature of sphere P increases at a faster rate than the temperature of sphere Q.

The heater remains switched on.

Figure 17 shows how the temperature of sphere P changes with time.

Explain why the temperature of P reaches a constant value, even though the heater remains switched on.

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.