1. 1
   A woman looks at her reflection in a flat bathroom mirror. She holds up a printed page with a single word on it in front of the mirror and reads the reflected word.

   (a)

   What type of image does a flat (plane) mirror produce?

   [1 mark]

   • AReal, inverted, and the same size as the object
   • BVirtual, upright, and laterally inverted
   • CReal, upright, and magnified
   • DVirtual, inverted, and diminished

   (b)

   A ray of light from a lamp hits the flat mirror and reflects into the woman's eyes. Which law correctly describes how this ray of light behaves when it reflects?

   [1 mark]

   • AThe angle of incidence is always greater than the angle of reflection
   • BThe angle of reflection depends only on the colour of the light
   • CThe angle of incidence equals the angle of reflection, both measured from the mirror surface
   • DThe angle of incidence equals the angle of reflection, both measured from the normal

   (c)

   Explain why the printed word appears reversed (back to front) when the woman views it in the mirror, and state what is meant by the 'normal' at the mirror's surface.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A submarine periscope contains two flat mirrors, each tilted at 45° to the vertical, fixed at the top and bottom of a long vertical tube. Light from above the water surface enters the top of the tube, reflects off the upper mirror, travels down the tube, and reflects off the lower mirror to reach the sailor's eye.

   (a)

   Which physical law explains why each mirror redirects the light by exactly 90°?

   [1 mark]

   • AThe law of reflection
   • BThe law of conservation of energy
   • CNewton's Third Law
   • DThe law of refraction

   (b)

   To work out the angle at which the light reflects off each 45° mirror, which construction line must first be drawn at the point where the light ray strikes the mirror?

   [1 mark]

   • AA line parallel to the mirror surface
   • BA line joining the top and bottom mirrors
   • CThe normal, perpendicular to the mirror surface
   • DA line representing the sailor's line of sight only

   (c)

   Describe, using the law of reflection, why light travelling horizontally into the top of the periscope ends up travelling horizontally again after leaving the bottom mirror, having changed direction by a total of 180°.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A solar power engineer sets up a large flat mirror, called a heliostat, that reflects sunlight onto a receiver at the top of a central tower. At a particular moment, sunlight strikes the mirror at an angle of incidence of 35° to the normal.

   (a)

   State the angle of reflection of the sunlight at this moment, and explain how you determined this value.

   [3 marks]

   (b)

   As the day goes on, the direction of the incoming sunlight gradually changes. Explain why the engineer must continually adjust the tilt of the mirror throughout the day to keep the reflected sunlight hitting the receiver on the tower.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A hairdresser positions two flat mirrors facing each other: a large mirror on the wall in front of the customer's chair, and a smaller hand-held mirror held up behind the customer's head. Light from the back of the customer's head reflects off the hand-held mirror, travels across the salon, and reflects a second time off the large wall mirror before reaching the customer's eyes, allowing her to see the back of her own head.

   (a)

   Explain, using the law of reflection, how light travels from the back of the customer's head to her eyes via the two mirrors.

   [6 marks]

   (b)

   A single plane mirror produces a laterally inverted image. Discuss whether the final image the customer sees of the back of her head, after light has reflected off both mirrors, is laterally inverted compared with reality, or appears the correct way round, explaining your reasoning.

   [6 marks]

   Total for question 4: 12 marks

End of questions