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Year 8 Science — Mirrors and lenses

Tell concave from convex for both mirrors and lenses, use the laws of reflection to find an angle, and say which of them gathers a beam and which spreads it.

Name: ________________________

  1. 1.Why is a convex mirror, rather than a plane one, fitted as a vehicle's side-view mirror?

    • a) It is cheaper to make than a plane mirror of the same size
    • b) It shows the traffic behind at a larger size
    • c) It shows the traffic behind the right way up, which a plane mirror cannot
    • d) It shows a much wider area of the road behind

  2. 2.You are handed a magnifying glass. Which kind of lens is it?

    • a) A convex lens
    • b) A spherical mirror
    • c) A plane lens
    • d) A concave lens

  3. 3.How does a concave lens differ from a convex one to look at?

    • a) It is thicker in the middle than at the edges
    • b) It is not transparent
    • c) It is thicker at the edges than in the middle
    • d) It is the same thickness throughout

  4. 4.A ray strikes a mirror, and the grey upright line is the normal at that point. Tap the angle of incidence.

    Write the number of the part.

    12

  5. 5.A ray of light strikes a mirror at an angle of 35° to the normal. What is the angle of reflection, in degrees? Answer with a number.

  6. 6.Parallel beams of light fall on each of these. Sort them by what happens to the beams afterwards.

    Groups: Converges the beam · Diverges the beam

    • Concave mirror
    • Concave lens
    • Convex lens
    • Convex mirror

  7. 7.Each of these is a mirror doing a job. Sort them by which kind of mirror is used.

    Groups: Concave mirror · Convex mirror

    • A dentist's mirror
    • The side-view mirror of a vehicle
    • A road safety mirror at a bend
    • The reflector of a torch
    • A store's surveillance mirror

  8. 8.The laws of reflection were worked out with a plane mirror. Which mirrors do they hold for?

    • a) Plane and concave mirrors, but not convex ones
    • b) Plane mirrors and nothing else
    • c) Curved mirrors, but not plane ones
    • d) Plane, concave and convex alike

Answer key — Year 8 Science — Mirrors and lenses

  1. 1. d) It shows a much wider area of the road behind
  2. 2. a) A convex lens
  3. 3. c) It is thicker at the edges than in the middle
  4. 4. 1 — Angle of incidence
  5. 5. 35
  6. 6. Concave mirror → Converges the beam; Convex lens → Converges the beam; Convex mirror → Diverges the beam; Concave lens → Diverges the beam
  7. 7. The reflector of a torch → Concave mirror; A dentist's mirror → Concave mirror; The side-view mirror of a vehicle → Convex mirror; A road safety mirror at a bend → Convex mirror; A store's surveillance mirror → Convex mirror
  8. 8. d) Plane, concave and convex alike