Question

A student investigates the motion of pollen grains in water seen through a microscope.

The student observes that the pollen grains constantly move short distances in random directions.

(a) Fig. 9.1 shows the pollen grains suspended in water.

(i) State the name given to the motion of these pollen grains.

(ii) Explain why the pollen grains constantly move short distances in random directions.

(b) The microscope uses a thin converging lens to produce an image. Fig. 9.2 shows a thin converging lens.

(i) Draw a ray diagram on Fig. 9.2 to show the formation of a real image. Label the image with the word image.

(ii) The image formed is a real image. Describe one difference between a real image and a virtual image.

(c) The visible light that passes through the lens is part of the electromagnetic spectrum.

(i) State the speed of visible light in a vacuum.

(ii) γ-rays and radio waves are also part of the electromagnetic spectrum. Place ticks (✓) in the boxes in Table 9.1 to show which statements are true for γ-rays and radio waves.