Ray Model of Light Flashcards
(29 cards)
What is a ray?
The path along which light energy travels.
What is a beam of light?
A bundle of light rays.
What are the characteristics of images formed by plane mirrors?
Same size as object, upright, laterally inverted, virtual, image distance from mirror=object distance from mirror.
What is an incident ray?
The angle of light approaching a reflecting surface.
What is the point of incidence?
The point where the incident ray meets the reflecting surface.
What is the reflected ray?
The ray of light bouncing off the reflecting surface.
What is the normal?
The ling perpendicular to the reflecting surface and passing through the point of incidence.
What is the angle of incidence?
The angle between the incident ray and the normal, usually represented by i.
What is the angle of reflection?
THe angle between the reflected ray and the normal, usually represented by r.
What are the laws of reflection?
- Angle of incidence = angle of reflection
- Incident ray, reflected ray and normal all lie on the same plane.
Name uses of plane mirrors.
- interior design: on a wall, makes a room look bigger
- optical testing
- checking one’s appearance
Characteristics of images formed by convex mirror?
Images are upright and diminished. Allows a wider field of vision.
Name uses of convex mirrors.
- security mirror in shop: allows staff to observe a large area of shop
- mirrors at blind corners of roads
Characteristics of images formed by concave mirrors?
Object near —> upright+magnified
object further away —> inverted
Name uses of concave mirrors.
- dentist’s mirror: magnify image of teeth
- make-up mirror: make a person’s face lok bigger for easier application of makeup
How is light reflected on a smooth surface?
A parallel beam of light that falls onto a smooth surface will be reflected as a parallel beam. The normals at all points of incidence are parallel. Hence, all rays have the same incident and reflected angles. A sharp image is produced.
How is light reflected on a rough surface?
If a parallel beam of light falls onto a rough surface, it is reflected in many directions as the normals at all points of incidence are not parallel. As the angle of incidence at each point is different, the angle of reflection for every ray will be different. This does not produce a sharp image.
What is refraction?
The bending of a light ray as it passes from one medium to another.
What causes refraction?
Light travels at different speeds in different optical media.
When the light ray travels from an optically less dense medium into an optically denser medium, it slows down and bends towards the normal.
How does misperception of depth occur?
The light rays travelling from water to air refract away from the normal.
However, our brain tends to tell us that light rays travel in a straight line.
The light rays emerging from the water surface appear to diverge from a point above the object.
The observer sees the image of the object at a shallower depth.
What is dispersion?
The splitting of white light into its component colours.
ow does dispersion occur?
When a beam of white light passes through a glass prism, the light splits up and disperses into a spectrum.
What colours travels the fastest and slowest through a prism?
Red travels fastest and bends the least.
Violet travels slowest and bends the most?
What are the 7 colours in the spectrum?
Red, orange, yellow, green, blue, indigo, violet.
