# Physics: Light and Geometric Optics Megan Pudiquet
Get Started. It's Free Physics: Light and Geometric Optics ## 1. Phenomena of Light 2: Lenses and Refraction

1.7.1. \

### 1.16. Calculating the Index of Refraction and Speeds of Light in various media:

1.16.1. n=Va/Vg=c/v

## 2. The Nature of Light

### 2.2. Waves:

2.2.1. Crest: Highest point in the wave.

2.2.2. Trough: Lowest point in the wave.

2.2.3. Rest position: No wave.

2.2.4. Wavelength (λ): Distance from the same place in consecutive waves. (E.g. The distance from crest to crest.)

2.2.5. Amplitude: Height or depth of the wave from rest to the crest, or from rest to the trough of the wave.

2.2.6. Frequency: The rate of repetition of the wave.

2.5.1. Violet

2.6.1. Red

### 2.7. What 6 Colours do you see when white light is shone through the prism.

2.7.1. Red, Orange, Yellow, Green, Blue, Violet

### 2.8. What is the order of the colours?

2.8.1. Red, Orange, Yellow, Green, Blue, Violet

### 2.9. Where do you think the colours come from?

2.9.1. When white light hits every wall of a prism, it creates arrays of colour.

### 2.10. In what phenomena in nature do you see the same colour formation?

2.10.1. When sunlight passes through a waterfall.

### 2.17. Rectilinear Propagation: This is the tendency for light to travel in straight lines especially in a homogenous transparent medium. In general, light travels in straight lines until it strikes something. The properties of that something determines what will happen to the light.

2.17.1. Transparent: Transparent materials transmit light freely - light passes right through it (E.g. glass)

2.17.2. Translucent: Translucent materials transmit some light, absorb and reflect some light. Therefore, you cannot quite see right through it. (E.g. Frosted glass)

2.17.3. Opaque: Opaque materials absorb and reflect all light. (E.g. A blackboard)

## 3. Phenomena of Light 1: Mirrors and Reflection

### 3.1. Mirrors: A mirror is a non-luminous object with a smooth shiny surface that reflects light in such a way that images form.

3.1.1. Plane Mirror: Any mirror that has a flat reflective surface is called a plane mirror. We use plane mirrors when we look at our reflections for our family purposes. Light bounces off mirrors in a similar way to how a hockey puck bounces off the boards of a ice rink. The reflections in plane mirrors form images that appear to be behind the mirror (about the same distance as the object is from the mirror) but the image looks the same size and shape as the object itself.

3.1.2. Curved Mirrors: Mirrors that are outward-curved (convex mirrors) or inward-curved (concave) surfaces also form images. These images often produce very strange looking images that are different in size the shape than the object, but these mirrors can also be used in many optical devices.

### 3.2. Light obeys two laws of reflection, and if we use these laws to draw a light ray diagram we can see what images can be formed in planed mirrors.

3.2.1. The incident ray, the normal, and the reflected ray all lie on the same plane.

3.2.2. The angle of the incidence equals the angle of reflection. Therefore, if a light ray struck a mirror at a 45º angle, then it would bounce back at that same angle.

3.2.3. The angles of incidence and reflection are between the normal and the incident and reflective rays respectively.

### 3.4. There are four main characteristics that describe images:

3.4.1. Size: The image can be smaller, larger or the same as the object.

3.4.1.1. Magnification: Magnification is the measure of how much larger or smaller an image is compared with the object itself.

3.4.2. Orientation or Attitude: The image can be upright (the same way up) or inverted (upside-down) in comparison to the object.

3.4.3. Location: In front of the mirror or in the back of the mirror. This can be used to determine the type of image.

3.4.4. Type: The type are location of an image are related. The type of image often depends on its location (for instance, in the mirror, or on a screen).

3.4.4.1. Real Image: The image can be seen on a screen (E.g PowerPoint projector) - the image is in front of the mirror.

3.4.4.2. Virtual Image: The image can only be seen by looking at/through the optical device (E.g. Image from a mirror) - the image is behind the mirror.

### 3.6. Characteristics of Images in Plane Mirrors:

3.6.1. Size: The same size as the object

3.6.2. Orientation/Attitude: Upright (the same direction as the object)

3.6.3. Location: The image looks as though it is behind the mirror

3.6.4. Type: Virtual

### 3.7. An easier way to find and draw images in a plane mirror:

3.7.1. Measure the perpendicular distance from a point on an object to the mirror.

3.7.2. Extend the measurement the same distance from a point on the other side of the mirror. That is where the image of that point appears in the mirror.

3.7.3. Trace the outline from point to point.

### 3.16. Calculating Magnification:

3.16.1. Magnification = image height/object height M=hi/ho

3.16.2. Magnification = image distance/ object distance M=di/do

### 3.18. Drawing a Concave Mirror Ray Diagram

3.18.1. The first ray of a concave mirror ray diagram travels from a point on the object parallel to the principal axis. Any ray that is parallel to the principal axis will reflect through the the focal point on a converging mirror.

3.18.2. The second ray travels from a point on the object toward the focal point. Any ray that passes through the focal point on a converging mirror will be reflected back parallel to the principal axis.

3.18.3. Draw the real image where the rays intersect.

### 3.19. Drawing a Convex Mirror Ray Diagram

3.19.1. The first ray of a convex mirror ray diagram travels from a point on the object parallel to the principal axis. Any ray that is parallel to the principal axis will appear to have originated from the focal point on a diverging mirror.

3.19.2. The second ray travels from a point on the object toward the focal point. Any ray that is directed at the focal point on a diverging mirror will be reflected back parallel to the principal; axis.

3.19.3. Draw the virtual image where the rays appear to intersect.