New
New
Year 8

Reflected images

I can describe and explain the properties of reflections in a plane mirror, and draw diagrams to show how reflections form.

New
New
Year 8

Reflected images

I can describe and explain the properties of reflections in a plane mirror, and draw diagrams to show how reflections form.

Lesson details

Key learning points

  1. Reflections are the same size as the object, upright, and the same distance behind the mirror as the object is in front.
  2. In a plane mirror, reflections appear laterally inverted compared to the object when it is facing us.
  3. Mirrors reflect what is in front of them. Reflections are laterally inverted as objects are turned to face a mirror.
  4. Reflections are virtual images; they appear where light rays seem to have come from, not where they actually come from.
  5. Virtual rays show where light rays appear to have come from; they are drawn as dashed lines.

Keywords

  • Image - a representation of an object

  • Reflection - (1) the process of light ‘bouncing off’ a surface (2) an image seen in a mirror

  • Laterally inverted - describes an image that has been ‘flipped’ horizontally

  • Virtual ray - a dashed line drawn to show where light seems to be (but is not actually) coming from

  • Virtual image - an image that can be seen but not projected onto a screen

Common misconception

Mirrors must somehow turn images around or ‘flip’ them to make reflections laterally inverted.

Explicitly teach that a mirror merely (and passively) reflects what is directly in front of each part of it. Pupils can observe the reflection of text on clear plastic: the image is the same as what is seen looking through the back of the text.

When teaching how to draw ray diagrams of reflection, all pupils will benefit from a scaffolded and stepwise approach involving live teacher modelling (perhaps using a visualiser) and pupil practice of individual component steps, e.g. on mini-whiteboards (to allow easy checking of all pupils' work).
Teacher tip

Equipment

Teachers could consider making mirrors, clear plastic and pens (for writing on clear plastic) available for use this lesson to demonstrate some of the ideas covered.

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Lesson video

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6 Questions

Q1.
Which of the following is a word meaning ‘representation of a real object’?
Correct answer: image
normal
objective
imaginary object
Q2.
Which of the following is a definition of the word ‘inverted’?
reflected
rotated a half turn
rotated a full turn
Correct answer: turned upside–down
Q3.
Which of the following are definitions of the word ‘reflection’?
Correct answer: What we can see in a mirror.
An object that is in front of a mirror.
Correct answer: What happens when light ‘bounces off’ a surface.
Light changing direction when it enters a material.
Q4.
Which of the following describe the way a plane (flat) mirror reflects light?
Correct answer: If the incident rays are parallel, then the reflected rays are parallel.
If the incident rays are parallel, then the reflected rays are not parallel.
If the incident rays are not parallel, then the reflected rays are parallel.
Correct answer: If the incident rays are not parallel, then the reflected rays are not parallel.
Q5.
In the laws of reflection, which of the following statements comparing the angle of incidence and angle of reflection are correct?
Correct answer: Both angles are in the same plane.
Both angles are in different planes.
The angles are on opposite sides of the mirror.
Correct answer: The angles are on opposite sides of the normal.
Q6.
A pupil holds up a white screen at a short distance from a filament bulb that is switched on. Which of the following statements explains why a representation of the bulb does not appear on the screen?
The light hitting the screen is too dim.
The light hitting the screen is too bright.
Correct answer: Light from each point on the bulb hits every point on the screen.
Light from each point on the bulb hits only one point on the screen.

6 Questions

Q1.
A door is 4 m from a mirror. What is the distance between the door and the place where its reflection appears to be?
2 m
4 m
6 m
Correct answer: 8 m
Q2.
The picture shows four people and a cat looking at a mirror. Who can see the cat in the mirror?
An image in a quiz
Alex
Andeep
Correct answer: Laura
Sofia
nobody
Q3.
A pupil has a piece of card with the text ‘HELLO’ on it, as shown. They flip it around horizontally so that it faces a mirror. Which of the following reflections do they see in the mirror?
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz
An image in a quiz
An image in a quiz
Q4.
Which of the following describes reflections seen in mirrors?
If an object is on the right, its image is on the left.
The image of an object can be larger than the object.
The image of an object can be smaller than the object.
Correct answer: If an object is farther from the mirror, its image is further from the mirror.
Q5.
Which of the following statements about virtual rays and virtual images are correct?
Virtual rays are drawn as solid lines.
Virtual rays show paths travelled by light.
Correct answer: Virtual rays do not show paths travelled by light.
Correct answer: A virtual image cannot be projected onto a screen.
Q6.
Which of the following explains why we see images in mirrors?
The mirror creates light which produces images.
Our brain imagines reflections because we are expecting to see them.
Light from objects passes through the mirror to make images behind it.
Correct answer: Our eyes trace back to where the reflected rays appear to have come from.