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NOTES ON LIGHT - EXAMINED IN FULL IN JUNE EXAMS

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NOTES ON LIGHT - EXAMINED IN FULL IN JUNE EXAMS

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Rule 2 - REFLECTION (REGULAR VS DIFFUSE)

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Rule 2 - REFLECTION (REGULAR VS DIFFUSE)

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An object can be seen when the light that is reflected or emitted by an object enters the eye.

If no light enters the eye, the absence of light is interpreted as darkness and the object appears to be black.

Light travels in straight lines (unless acted upon by a surface or force).

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Uniform Acceleration in One Dimension: Motion Graphs

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A simple pinhole camera can be made out of a shoe box painted black inside. Cut square holes out of each end of the box. Fix a sheet of aluminium foil over one hole and make a small, round hole (aperture) in the foil with a pin. Paste a piece of tracing paper over the other hole to serve as a screen. Aim the aperture at an object and observe the image produced on the tracing paper.

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What characteristic of light explains why an inverted image of an object forms in a pinhole camera?

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Light falling on an object can be transmitted (pass through), absorbed and/or reflected.

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ABSORPTION, REFLECTION & TRANSMISSION OF LIGHT

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ABSORPTION, REFLECTION & TRANSMISSION OF LIGHT

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Light Absorption, Reflection, and Transmission

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2 TYPES OF REFLECTION: REGULAR VS DIFFUSE

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2 TYPES OF REFLECTION: REGULAR VS DIFFUSE

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SPECULAR (REGULAR) VS DIFFUSE

KNOW:

Laws of reflection

1.  The angle of incidence is equal to the angle of reflection.

2. The incident ray, normal and reflected ray, at the point of incidence (B) all lie in the same plane.

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Properties of a plane (flat) mirror image

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Properties of a plane (flat) mirror image

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1.       Laterally inverted.
2.       Upright.
3.       Same size as object.
4.       As far behind the mirror as the object is in front.

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PERISCOPES!

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LIGHT AS A WAVE (ELECTRIC+MAGNETIC FIELD)

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LIGHT AS A WAVE (ELECTRIC+MAGNETIC FIELD)

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LIGHT = ELECTROMAGNETIC WAVES
Consists of 2 perpendicular waves:

a vertical electric field and

a horizontal magnetic field,

in phase with each other.

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v = f. λ                        where, v is speed
f is frequency
λ is wavelength

HOW TO DERIVE THE WAVE EQUATION:
We know:                speed = distance / time
For a wave:             speed = wavelength / time
= λ / T
= λ x 1/T
= λ x f
v = fλ

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GCSE Physics Revision: The wave equation

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Radiation of all frequencies travels at the same velocity through space. The speed of light in vacuum, c, is equal to 3 x 10⁸ m.s−1.

The wavelength and frequency of these waves can be calculated using the wave equation,

c = f λ

where c is the speed of light = 3 x 10⁸ m.s−1
f is the frequency measured in hertz (Hz)
λ is wavelength measured in metres (m)

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Real vs apparent depth

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Boats and boating--Equipment and supplies

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2 PROPERTIES OF WAVE CHANGES WHEN LIGHT ENTERS GLASS:

Speed of light wave DECREASES

Wavelength of light wave DECREASES

Because frequency stays constant

by v=f.lamba

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TOTAL INTERNAL REFLECTION = the complete reflection of a light ray reaching an interface with a less dense medium when the angle of incidence exceeds the critical angle.

CRITICAL ANGLE = the size of an incident angle that produces a refracted angle of 90°.

2 CONDITIONS UNDER WHICH T.I.R OCCURS:

Light must travel from more dense to less dense medium.

Angle of incidence must be BIGGER THAN CRICITAL ANGLE of the light beam.

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Total Internal Reflection Demo: Optical Fibers

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Total internal reflection through prisms inside Binoculars

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Total internal reflection through prisms inside Binoculars

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HOW A SPHERICAL RAINDROP DISPERSES LIGHT

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HOW A SPHERICAL RAINDROP DISPERSES LIGHT

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Many objects contain atoms capable of either selectively absorbing, reflecting or transmitting one or more frequencies of light.

The frequencies of light that become transmitted or reflected to our eyes will contribute to the color that we perceive.

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Refractive index = the ratio of the speed of light in a vacuum to its speed in a refractive       material, where bending of a ray of light occurs when passing from a medium into another with different density.

Optical density = a measure of the refracting power of a medium.

Total internal reflection = the complete reflection of a light ray reaching an interface with a less dense medium, when the angle of incidence exceeds the critical angle.

Critical angle = The angle of incidence where the angle of refraction is 90°.

Normal = the line that is perpendicular to the plane of the surface.

c = 299 792 458 m.s⁻¹ ≃ 3 x 10 8 m.s⁻¹

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OBJECTS LOOK MORE SHALLOW IN WATER DUE TO REFRACTION

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OBJECTS LOOK MORE SHALLOW IN WATER DUE TO REFRACTION

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7 colours (ROYGBIV) of light fall onto any object, it absorbs 6 colours that is not its own and reflects the colour of light similar to its own colour.
Key: ROYGBIV = Red, Orange, Yellow, Green, Blue, Indigo, Violet

Plants are green (G):

They absorb ROYBIV

They reflect G

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LIGHT WORKSHEET

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HOW RAIN DROPS REFRACT LIGHT TO FORM A RAINBOW

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HOW RAIN DROPS REFRACT LIGHT TO FORM A RAINBOW

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HOW A PRISM REFRACTS LIGHT INTO ROYGBIV - DISPERSION

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HOW A PRISM REFRACTS LIGHT INTO ROYGBIV - DISPERSION

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ABC Zoom - Refraction: why glass prisms bend and separate light

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Newton's Light Spectrum Experiment | Earth Science

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HOW A RAINDROP FORMS A RAINBOW - VIA DISPERSION OF LIGHT

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HOW A RAINDROP FORMS A RAINBOW - VIA DISPERSION OF LIGHT

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7 colours (ROYGBIV) of light fall onto any object, it absorbs 6 colours that is not its own and reflects the colour of light similar to its own colour.
Key: ROYGBIV = Red, Orange, Yellow, Green, Blue, Indigo, Violet

Plants are green (G):

They absorb ROYBIV

They reflect G

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Complementary pairs of light colors are those colors that are exactly opposite each other on the diagram:

red and cyan

magenta and green

blue and yellow

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Lens filters are transparent

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FILTERS VIDEO - SUBTRACTIVE COLOURATION (SELECTIVE ABSORBTION)

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FILTERS VIDEO - SUBTRACTIVE COLOURATION (SELECTIVE ABSORBTION)

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Colour and Colour Filters - GCSE Physics

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COLOUR NOTES - not examined now in June exam

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COLOUR NOTES - not examined now in June exam

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NOTES - LENSES (this section of lenses is not examined)

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NOTES - LENSES (this section of lenses is not examined)

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light