Unit 5: Ray Model of Light Flashcards

Flashcards covering the Ray Model of Light unit, including reflection, refraction, mirrors, dispersion, and electromagnetic radiation.

What are the primary characteristics of light propagation?

Light travels in a straight line, and from a source, a countless number of light rays travel away in straight lines.

What is the difference between luminous and non-luminous objects?

Luminous objects, such as the sun and fireflies, can emit light on their own. Non-luminous objects do not emit light but instead reflect light from their surroundings.

Define the three types of light beams mentioned in the text.

1. Divergent beam: Light rays spread out from a source. 2. Convergent beam: Light rays move towards a focal point. 3. Parallel beam: Light rays travel parallel to one another.

What is the speed of light in a vacuum?

The speed of light in a vacuum is $3 \times 10^8\,m/s$.

Define 'Reflection' and its main components.

Reflection is the bouncing of light rays off a surface. Components include the incident ray (strikes the surface), reflected ray (away from the surface), and the normal (line at $90^{\circ}$ to the surface).

State the two Laws of Reflection.

1. The incident ray, reflected ray, and normal at the point of incidence lie on the same plane. 2. The angle of incidence ($i$) is equal to the angle of reflection ($r$).

What are five characteristics of images formed by a plane mirror?

1. Virtual (cannot be captured on screen), 2. Upright, 3. Laterally inverted, 4. Same size as the object, 5. Equal distance from the mirror as the object.

Distinguish between regular and diffuse reflection.

Regular reflection occurs on smooth surfaces with organized, parallel reflected rays. Diffuse reflection occurs on uneven surfaces where light reflects in many random directions, though each ray still obeys the laws of reflection.

What characterizes a convex mirror and what are its common applications?

Convex mirrors (divergent) curve outwards, forming images that are diminished, upright, and virtual. Applications include car side mirrors, blind corner mirrors, and surveillance mirrors because they provide a wider field of view.

What characterizes a concave mirror and what are its common applications?

Concave mirrors (convergent) curve inwards and focus light. They form images that are magnified, upright, and virtual (when close). Applications include microscopes, dentist mirrors, and cosmetic mirrors.

Define 'Refraction'.

Refraction is the bending of light rays at the boundary between two different transparent materials due to a change in the speed of light as it passes from one material into another.

Explain the relationship between optical density and light speed.

Light travels slower in an optically denser medium and faster in an optically less dense medium.

How does light bend when moving between media of different densities?

When moving from less dense to denser, light slows down and bends towards the normal ($i > r$). When moving from denser to less dense, light speeds up and bends away from the normal ($i < r$).

What happens when a light ray travels perpendicularly ($90^{\circ}$) between two media?

There is no refraction of light; the light ray does not change its direction of travel.

Define 'Dispersion of light'.

The splitting of white light into its seven component colors (red, orange, yellow, green, blue, indigo, violet) as they pass through a medium like a glass prism.

What is a 'spectrum' in the context of light?

A spectrum is the ordered arrangement of colors (ROYGBIV) that appears after white light is dispersed, such as in a rainbow.

Why do different colors of light bend at different angles during dispersion?

Because components of white light slow down to different extents. The red component slows down the least (least bending), while the violet component slows down the most (most bending).

What are the applications and harmful effects of Ultraviolet (UV) radiation?

Applications: Vitamin D production in skin, sterilizing water and medical equipment. Harms: Overexposure can cause skin cancer and eye damage.

How is infrared radiation utilized in healthcare?

It is used in thermal imaging cameras to screen for fever by detecting the infrared radiation (heat) emitted by a person.

What environmental impact is associated with infrared radiation?

Infrared radiation trapped in the atmosphere can cause climate change, leading to increased Earth temperatures and altered weather patterns.