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Describing images size

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Describing images size

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    2. Describing images – size

    3. Describing images – orientation

    4. Describing images – real or virtual? Teacher notes Ask students to think of examples of real and virtual images to test their understanding.Teacher notes Ask students to think of examples of real and virtual images to test their understanding.

    5. Describing images – quiz Teacher notes This activity tests the students’ understanding of image formation and description. It could be used as a plenary or revision exercise, with students answering individually, or in teams.Teacher notes This activity tests the students’ understanding of image formation and description. It could be used as a plenary or revision exercise, with students answering individually, or in teams.

    7. What is refraction? Photo credit: © 2009 Shutterstock, Roman SigaevPhoto credit: © 2009 Shutterstock, Roman Sigaev

    8. Refraction in a glass block Teacher notes This exercise should act as revision from KS3 Science. By activating the angle measurements in stages, students are given a chance to identify the various elements of the experiment. Initially they should try to define the normal, name the rays and angles shown and describe the relative angle size. Revealing the angles at the air to glass boundary will act to clarify these points to students. Students can then be challenged to identify i2 and r2, before revealing them to the class.Teacher notes This exercise should act as revision from KS3 Science. By activating the angle measurements in stages, students are given a chance to identify the various elements of the experiment. Initially they should try to define the normal, name the rays and angles shown and describe the relative angle size. Revealing the angles at the air to glass boundary will act to clarify these points to students. Students can then be challenged to identify i2 and r2, before revealing them to the class.

    9. Refraction – labelling diagrams

    10. Refraction summary Teacher notes This activity could be used as a plenary or revision exercise to check students’ understanding of refraction, and to test their ability to extract valuable information from a table.Teacher notes This activity could be used as a plenary or revision exercise to check students’ understanding of refraction, and to test their ability to extract valuable information from a table.

    11. Wavelength and speed effects Teacher notes Draw the students attention to the way in which a change in direction of the wave coincides with a change in speed and wavelength. Ask students to identify the type of wave produced (transverse) and highlight that this is the same as a light wave. What other similarities can the students note between the behaviour of water waves and light waves?Teacher notes Draw the students attention to the way in which a change in direction of the wave coincides with a change in speed and wavelength. Ask students to identify the type of wave produced (transverse) and highlight that this is the same as a light wave. What other similarities can the students note between the behaviour of water waves and light waves?

    12. A model for refraction Teacher notes This animation is designed to clearly explain the link between wave speed, direction and wavelength. At the end of stage one students could be challenged to predict what will happen to the column. Encourage them to explain why they have predicted this, and to describe the soldiers as a wave, using appropriate terms.Teacher notes This animation is designed to clearly explain the link between wave speed, direction and wavelength. At the end of stage one students could be challenged to predict what will happen to the column. Encourage them to explain why they have predicted this, and to describe the soldiers as a wave, using appropriate terms.

    13. Speed of light Teacher notes Students could be asked to research the speed of light in each material themselves. The idea of light taking time to reach its destination may also be discussed. The concept of light years could be introduced, and the students should realise that the light we see from the stars in the sky was actually emitted thousands of years ago. Teacher notes Students could be asked to research the speed of light in each material themselves. The idea of light taking time to reach its destination may also be discussed. The concept of light years could be introduced, and the students should realise that the light we see from the stars in the sky was actually emitted thousands of years ago.

    14. Refractive index Teacher notes There are no units for refractive index.Teacher notes There are no units for refractive index.

    15. Snell’s Law Teacher notes Students should note that the equation can be easily rearranged to find both the angles of incidence and refraction if required. Students could measure the angle of incidence and refraction in a range of different materials and calculate the refractive index of these themselves.Teacher notes Students should note that the equation can be easily rearranged to find both the angles of incidence and refraction if required. Students could measure the angle of incidence and refraction in a range of different materials and calculate the refractive index of these themselves.

    16. Using Snell’s Law

    17. Using Snell’s Law

    18. Using Snell’s Law

    20. Total internal reflection

    21. Total internal reflection – a recap Teacher notes This exercise is designed to test the students’ knowledge of total internal reflection covered in GCSE core science. Students could vote on the correct position of each label. There is a possible ambiguity if ‘refraction’ appears before ‘refraction along the boundary’, so allow students to adjust their answers appropriately if this causes confusion.Teacher notes This exercise is designed to test the students’ knowledge of total internal reflection covered in GCSE core science. Students could vote on the correct position of each label. There is a possible ambiguity if ‘refraction’ appears before ‘refraction along the boundary’, so allow students to adjust their answers appropriately if this causes confusion.

    22. Optical fibres Teacher notes The students should identify the need for the cladding to have a lower refractive index than the core in order for total internal reflection to occur.Teacher notes The students should identify the need for the cladding to have a lower refractive index than the core in order for total internal reflection to occur.

    23. Critical angle in different materials Teacher notes Students could be asked to produce their own graph to establish the relationship between the refractive index and the critical angle.Teacher notes Students could be asked to produce their own graph to establish the relationship between the refractive index and the critical angle.

    24. Calculating the critical angle

    25. Calculating the critical angle – examples Teacher notes Ask the students to explain their answer in the repeat calculation. This should return an ‘error’ message on students’ calculators. This is because sin (x) has a maximum value of one, so the first material must have a higher refractive index than the second.Teacher notes Ask the students to explain their answer in the repeat calculation. This should return an ‘error’ message on students’ calculators. This is because sin (x) has a maximum value of one, so the first material must have a higher refractive index than the second.

    26. Total internal reflection – true or false?

    28. Prisms

    29. Speed of light in materials Teacher notes Q: Why doesn’t a glass block disperse light? A: It does by a small amount inside the block, but as the light leaves, it is refracted back into a white ray.Teacher notes Q: Why doesn’t a glass block disperse light? A: It does by a small amount inside the block, but as the light leaves, it is refracted back into a white ray.

    30. Dispersion – summary

    32. Glossary Glossary angle of incidence – The angle at which a light ray meets a mirror or boundary, measured from the normal. angle of reflection – The angle at which a light ray is reflected by a mirror, measured from the normal. angle of refraction – The angle, measured from the normal, at which a light ray is refracted at a boundary between one medium and another. concave mirror – A mirror that curves in at the centre. convex mirror – A mirror that curves out at the centre. critical angle – If the light hits a boundary between two materials at an angle greater than this, total internal reflection occurs. dispersion – The splitting of a light ray into its component colours by refraction. focal point – The point to which light rays parallel to the central axis are reflected by a concave mirror, or the point from which such light rays appear to have originated in a convex mirror. focal length – The distance between a curved mirror and its focal point. inversion – The reversal of an image so that it appears upside-down. lateral inversion – The reversal of an image so that the left-hand side appears to be on the right and the right-hand side appears to be on the left.# law of reflection – When light is reflected, the angle of incidence equals the angle of reflection. light – Electromagnetic waves that are detected by the eye. medium – A material through which light travels. normal – A line on a ray diagram drawn at right angles to the surface being hit by the light ray. real – An image which can be formed on a screen. refraction – The bending of light when it enters a different medium. refractive index – A measure of a medium’s ability to slow down light passing through it. Snell’s Law – A formula describing the relationship between the refractive index and the angles of incidence and refraction. total internal reflection – Reflection that occurs when light hits a boundary with a medium with a lower refractive index than the medium it is travelling through, at an angle greater than the critical angle. virtual – An image which cannot be formed on a screen. Glossary angle of incidence – The angle at which a light ray meets a mirror or boundary, measured from the normal. angle of reflection – The angle at which a light ray is reflected by a mirror, measured from the normal. angle of refraction – The angle, measured from the normal, at which a light ray is refracted at a boundary between one medium and another. concave mirror – A mirror that curves in at the centre. convex mirror – A mirror that curves out at the centre. critical angle – If the light hits a boundary between two materials at an angle greater than this, total internal reflection occurs. dispersion – The splitting of a light ray into its component colours by refraction. focal point – The point to which light rays parallel to the central axis are reflected by a concave mirror, or the point from which such light rays appear to have originated in a convex mirror. focal length – The distance between a curved mirror and its focal point. inversion – The reversal of an image so that it appears upside-down. lateral inversion – The reversal of an image so that the left-hand side appears to be on the right and the right-hand side appears to be on the left.# law of reflection – When light is reflected, the angle of incidence equals the angle of reflection. light – Electromagnetic waves that are detected by the eye. medium – A material through which light travels. normal – A line on a ray diagram drawn at right angles to the surface being hit by the light ray. real – An image which can be formed on a screen. refraction – The bending of light when it enters a different medium. refractive index – A measure of a medium’s ability to slow down light passing through it. Snell’s Law – A formula describing the relationship between the refractive index and the angles of incidence and refraction. total internal reflection – Reflection that occurs when light hits a boundary with a medium with a lower refractive index than the medium it is travelling through, at an angle greater than the critical angle. virtual – An image which cannot be formed on a screen.

    33. Anagrams

    34. Reflection and refraction quiz Teacher notes This multiple-choice quiz could be used as a plenary activity to assess students’ understanding of reflection and refraction. The questions can be skipped through without answering by clicking “next”. Students could be asked to complete the questions in their books and the activity could be concluded by completion on the IWB. Teacher notes This multiple-choice quiz could be used as a plenary activity to assess students’ understanding of reflection and refraction. The questions can be skipped through without answering by clicking “next”. Students could be asked to complete the questions in their books and the activity could be concluded by completion on the IWB.

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