Optics and Light Overview

Optics and Light

• Optics is the study of how light behaves, exploring its reflection, refraction and overall behaviour.
• Geometric optics deals with image creation, focusing on the relationships between angles and lines that describe light rays.
• A lens is an optical device designed to bend light in a specific way.
• Converging lenses bend light rays to converge at a point, while diverging lenses spread light rays apart.
• Mirrors reflect light, enabling us to see ourselves.
• Prisms, solid pieces of glass with polished surfaces, can alter the direction of light.

Reflection of Light

• Mirrors reflect light, allowing us to see images.
• The incident ray represents light falling onto the mirror, while the reflected ray is the light bouncing off the mirror.
• Specular reflection occurs when each incident ray bounces off in a single direction, producing a sharp, clear reflection.
• Diffuse reflection happens on non-shiny surfaces, causing a single ray of light to scatter in multiple directions.
• The law of reflection states that the angle of incidence equals the angle of reflection.

Refraction of Light

• Refraction happens when light bends as it transitions from one material to another, like from air to water.
• The index of refraction (n) measures the ability of a material to bend light rays.
• Snell's Law defines the relationship between angles of incidence and refraction, and the index of refraction of both materials.

Dispersion of Light

• Dispersion occurs when white light passes through a prism, causing it to separate into different colours, due to each color having a different index of refraction.

Lenses and Images

• Lenses are optical devices that can create images by bending light.
• Converging lenses can form both real and virtual images.
• A real image forms when light rays from an object converge at a point to form a visible image that can be projected onto a screen.
• A virtual image is formed when light rays appear to diverge from a point, creating an image that cannot be projected.
• Diverging lenses create virtual, upright, and smaller images.

Optical Systems

• An optical system is composed of mirrors, lenses, prisms, or other elements working together to manipulate light for a specific function.
• The image's location, type, (real or virtual), and magnification, the amount of light collected, the sharpness, color, and distortion of the image, and the ability to adjust the image and record it are all aspects of optical systems.

Aberration in Optical Systems

• Defects in image quality are known as aberrations.
• Chromatic aberration occurs when different colors focus at different distances from the lens, causing a blurry image.
• Spherical aberration causes a blurry image because light rays farther from the axis focus at a different point than rays near the axis.
• Diffraction results in a point from an object being focused as a set of concentric rings surrounding a bright spot.
• The thin lens formula provides a mathematical method for determining the location of an image.

Telescopes

• Telescopes use lenses (or mirrors) to collect and focus light, magnifying distant objects.