Optics

• 1. Optics: lenses, mirrors, and electromagnetic spectrum Physics

2. Properties of Light

• Light travels in straight lines

• Light travels much faster than sound

• We see things because they reflect light into our eyes

• Shadows are formed when light is blocked by an object

3.

• Luminous and non-luminous objects

Aluminousobject is one that produces light. Anon-luminousobject is one that reflects light. 4. Visible spectrum 5. Visible Eac h co lor is a differe nt si ze w ave . Red the longest &violet the shortest

• Emitted by

• • The sun and other astronomical objects

• • Laser pointers

• • Light bulbs

• Detected by

• • Cameras

• • (film or digital)

• • Human eyes

• • Plants (red light)

• • Telescopes

RoyG.Biv 6. What are sun rays?

• The sun emits several kinds of electromagnetic radiation: Visible (Vis), Infrared (IR) and Ultra Violet (UV)

• Each kind is distinguished by a characteristic wavelength, frequency and energy

• Higher energy radiation can damage our skin

High EnergyLow Energy 7. Colour

• White light is not a single colour; it is made up of a mixture of the seven colours of ther a i n b o w .

We can demonstrate this by splitting white light with a prism: *Animation 8.

• The Law of Reflection

Angle of incidence = Angle of reflection The same !!! 9. Clear vs. Diffuse Reflection

• Smooth, shiny surfaces have aclearreflection:

Rough, dull surfaces have adiffuse reflection. Diffuse reflection is when light is scattered in different directions 10. Refraction

• The change in direction of a wave as is crosses the boundary between two media in which the wave travels at different speeds.

11. Convex lenses

• Refracts parallel light rays so they come together at a single point (convergence).

• Distance from center of lens to focal point = focal length.

• The thicker the middle of the lens the shorter the focal length.

12. Concave lenses

• Refracts the rays so they come apart.-Known as divergence.

• Always forms a virtual image.

• Show overhead ofconcave lens .