LIGHT OPTICS

Optics

A branch of physics that deals with the determination of behavior, and the properties of light. As well as how they interact with the matter. And the instruments used to detect it.

Ray Optics

Geometrical optics, describes light propagation in terms of rays.

Light

 A form of energy that is in the form of an electromagnetic wave. The sun is the primary source of light.

Reflection

Change in direction of light at an interface in-between 2 diff media, so the wave-front returns into a medium from which it was originated.

Basically when light bounces off of a surface

Law of reflection: The angle of incident ray is equal to the angle of the reflected ray.

Refraction

The bending of light when it passes from one medium to another.

When a ray of light passes obliquely from an optically DENSER medium to a less dense medium it is refracted AWAY from the normal.

When a ray of light passes obliquely from an optically LESS dense medium to a denser medium it is refracted TOWARDS the normal

n1 sin a = n1 sin B

Dispersion

When white light splits itself into its constituent colors through a prism.

BLUE SKY?

When sunlight reaches Earth’s atmosphere and is scattered in all directions by all the gases and particles in the air. Blue light is scattered more than the other colors because it travels as shorter, smaller waves. This is why we see a blue sky.

RED SUNSET

As the sun sets, sunlight must traverse a greater distance through our atmosphere, ROYGBIV encounters more and more atmospheric particles. This results in the scattering of greater amounts of yellow light. During sunset, the light passing through our atmosphere to our eyes tends to be the most concentrated with red and orange frequencies of light.

RAINBOW

This is due to a combination of reflection, refraction, and dispersion. When sunlight hits a rain droplet, some of the light is reflected. The electromagnetic spectrum is made of light with many different wavelengths, and each is reflected at a different angle. This, the spectrum is separated, producing a rainbow.

2 Types of mirrors

Plane mirrors: Flat surface

Spherical mirrors: Curved surface

• Convex

• Concave

Rays of light

Incident ray : The light that strikes the surface of the mirror

Reflected ray : The light ray that bounces from the surface of the mirror

Types of images

Virtual image: Occurs when light rays do NOT actually meet the image

• Orientation is upright

• Location is behind the mirror

Real image: Occurs when light rays actually intersect at the image

• Orientation is inverted or up-side-down

• Location is infront of the mirror

Plane mirrors

Distance from the image to the mirror is the same as the distance of the object to the mirror. It has a reversal effect on the reflected object.

Spherical mirrors

Convex is when the reflecting surface is the outer surface of a sphere.

When the incident rays travel parallel to the principle axis of a convex mirror, they DIVERGE when reflected and seem to originate at F. They are diverging mirrors

Concave is when the reflecting surface is the mirror surface of the sphere

When incident rays travel parallel to the principle axis of a concave mirror they CONVERGE at F when reflecting. They are converging mirrors.

Mirrors as part of sphere

Ray Diagrams

Ray Diagrams: CONCAVE

Orientation: Inverted

Image type: Real

Location: Between C and F in front of the mirror

Size: Diminished

Ray Diagrams: CONVEX

Orientation: Upright

Image type: Virtual

Location: Between the mirror and F behind the mirror

Size: Diminished

PLANE MIRRORS

image is…

• Same size

• upright

• virtual

CONCAVE MIRROR

caves inward

image is…

• (Close) Upright, larger

• (Far) inverted, smaller

close - Make up mirror

Far - telescope

CONVEX MIRROR

caves outward

image is…

• smaller

• upright

• virtual

i.e. security mirrors