1. 1
   A dancer stands 2 metres in front of a large plane (flat) mirror in a rehearsal studio and checks her posture.

   (a)

   Which statement correctly describes the image she sees of herself in the mirror?

   [1 mark]

   • AA virtual image, the same size as her, appearing 2 metres behind the mirror
   • BA real image, twice her size, appearing 2 metres in front of the mirror
   • CA virtual image, half her size, appearing 4 metres behind the mirror
   • DA real image, the same size as her, appearing on the surface of the mirror

   (b)

   Why can the image of the dancer in the plane mirror not be projected onto a screen placed behind the mirror?

   [1 mark]

   • ABecause the dancer is too far from the mirror for an image to form
   • BBecause the mirror absorbs all the light before it can form an image
   • CBecause plane mirrors do not reflect any light at all
   • DBecause the image is virtual, formed where light rays only appear to come from, rather than where they actually meet

   (c)

   State the law of reflection, and use it to explain why the dancer sees her image appearing to be exactly 2 metres behind the mirror's surface, the same distance as she is standing in front of it.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A lighthouse uses a large curved mirror behind its lamp to direct light out to sea. A technician is testing a smaller plane mirror sample using a ray box and a protractor. She directs a single ray of light at the plane mirror so that it strikes the surface at an angle of incidence of 35 degrees, measured from the normal.

   (a)

   At what angle, measured from the normal, will the reflected ray leave the mirror?

   [1 mark]

   • A55 degrees
   • B35 degrees
   • C70 degrees
   • D17.5 degrees

   (b)

   The technician draws a construction line perpendicular to the mirror's surface at the point where the light ray strikes it, in order to measure the angles accurately. What is the correct term for this construction line?

   [1 mark]

   • AThe reflected ray
   • BThe incident ray
   • CThe normal
   • DThe critical line

   (c)

   Describe how the technician could use the ray box, the plane mirror, a protractor and a sheet of paper to measure and confirm the law of reflection experimentally.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A shop fits two plane mirrors on adjacent walls at right angles to each other in a changing room, so that a customer standing in the corner can see a reflection of their own back.

   (a)

   (a) Using the law of reflection, describe qualitatively how light from the customer's back reaches their eyes after reflecting off both mirrors in turn.

   [3 marks]

   (b)

   Explain why this arrangement only works well if the two mirrors are positioned at exactly 90 degrees to each other, and suggest what would happen to the customer's ability to see their back if the angle between the two mirrors were changed to something other than 90 degrees.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A large periscope is built from two plane mirrors, each mounted at 45 degrees to the vertical tube of the periscope, one at the top and one at the bottom, allowing a person at the bottom of the tube to see over a tall wall.

   (a)

   Explain fully, using the law of reflection and the characteristics of images formed in a plane mirror, how light from an object beyond the wall travels through the periscope to the observer's eye, and describe the characteristics of the final image the observer sees.

   [6 marks]

   (b)

   An engineer proposes modifying the periscope by increasing the length of the vertical tube between the two mirrors, so the periscope can be used to see over an even taller wall, while keeping both mirrors at exactly 45 degrees. Explain fully, using the law of reflection, whether this change affects the direction in which the final image is seen by the observer, and explain what other practical consequence increasing the tube length might have for how much of the scene beyond the wall the observer can see at any one time.

   [6 marks]

   Total for question 4: 12 marks

End of questions