Chapter 8: Light and Optics Flashcards
Electromagnetic Waves:
transverse waves that consists of an oscillating electric field and an oscillating magnetic field
the two fields are perpendicular to each other and to the direction of propagation of the wave
Electromagnetic Spectrum:
lowest to highest
radio waves, microwaves, infarered, visible light, ultraviolet, x-rays, γ-rays (gamma rays)
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Visible Spectrum wavelengths:
400-700nm
ROYGBIV
Red = 700nm
V = 380nm
speed of light value:
c = 3.00 x 108 m/s
How is color expressed?
(ex. white)
Light that contains all the colors in equal intensity is white
Ex: an object that appears red is one that absorbs all colors of light except red
Rectilinear propagation:
when light travels through a homogenous medium and travels in a straight line
Reflection:
- definition
- light waves that are reflected…
- rebounding of incident light waves at the boundary of a medium
- Light waves that are reflected are not absorbed into the second medium, they bounce off the boundary and travel back through the first medium
Law of Reflection:
Law of reflection: Θ1 = Θ2
*Θ1 = incident angle Θ2 = reflected angle*
Both are measured from the normal: a line drawn perpendicular to the boundary of a medium
All angles are measured from the medium
Plane Mirrors - Images:
- real images
- virtual images
Real: if the light actually converges at the position of the image - Image can be projected on a screen
Virtual: only appears to be coming from the position of the image but does not actual converge there
Plane Mirrors:
- what are they
- what they don’t cause the light to do
- type of images they always create
- how does this image appear
1. Plane mirrors: flat reflective surfaces
- Do not cause convergence or divergence of light rays
- Always create virtual, upright images that are the same size as the object
- Image appears to be the same distance behind the mirror as the object is in front of it
Center of Curvature (c):
a point on the optical axis located at a distance equal to the radius of curvature r from the vertex of the mirror
Center of curvature would be the center of the spherically-shaped mirror if it were a complete sphere
Spherical Mirrors - Concave surface:
- where center of curvature and radius of curvature are located
- diverging or converging?
- Center of curvature and the radius of curvature are located in front of the mirror
- Converging mirrors
Spherical Mirrors - Convex surface:
- where center of curvature and radius of curvature are located
- diverging or converging?
- Center of curvature and the radius of curvature are behind the mirror
- Diverging mirrors
Focal length (f):
- what it is
- for all spherical mirrors
- distance between the focal point (F) and the mirror
- For all spherical mirrors f = r/2, where the radius of curvature r is the distance between C and the mirror
o + i
(definitions)
o: distance between the object and the mirror
i: distance between the image and the mirror
Relationship between f, o, i and r
Image Distance:
- if the image has a positive distance (i > 0)
- if the image has a negative distance (i < 0)
- If the image has a positive distance (i > 0) it is a real image - Implies that the image is in front of the mirror
- If the image has a negative distance (i < 0) it is virtual - Image is located behind the mirror
Magnification (m):
- what it is
- equation
- dimensionless value that is the ratio of the image distance to the object distance
Give ratio of the size of the image to the size of the object
Values of Magnification:
- negative magnification
- positive magnification
- |m| > 1
- |m| < 1
- |m| = 1
- Negative magnification: inverted image
- Positive magnification: upright image
- If |m| < 1 the image is smaller than the object (reduced)
- If |m| > 1 the image is larger than the object (enlarged)
- If |m| = 1 the image is the same size as the object
Ray Diagram for a Concave Mirror:
- a ray that strikes the mirror parallel to the axis
- a ray that passes through the focal point before reaching the mirror
- a ray that strikes the mirror at the point of intersection with the axis
4. any time an object is at the focal point of a converging mirror
- A ray that strikes the mirror parallel to the axis is reflected back through the focal point (green lines)
- A ray that passes through the focal point before reaching the mirror is reflected back parallel to the axis (red lines)
- A ray that strikes the mirror at the point of intersection with the axis is reflected back with the same angle measured from the normal (blue lines)
- Any time an object is at the focal point of a converging mirror, the reflected rays will be parallel and thus, the image will be at infinity
Ray Diagram for Concave Mirror:
Object is placed before F
diagram + image produced
Image produced:
real
inverted
magnified