# PH Light and Optics

## 54 terms

### electromagnetic waves

waves generated by oscillating electric charges and are composed of oscillating electric and magnetic fields

### 3*10⁸ m/s

speed of light in a vacuum (c)

### c=wavelength*frequency

relating frequency and wavelength to the speed of light

### radio, micro, infared, ROYGBIV, UV, X-ray, gamma

List all spectra of the electromagnetic spectrum from greatest wavelength to lowest

### 700 nm

wavelength of red light?

### 400 nm

wavelength of violet light?

### photon is a bundle of energy that is carried in EMR

bundle of energy that is carried in electromagnetic radiation

### E=hc/wavelength=hf

solving for the energy of a photon

### angle of reflection is equal to the angle of incidence, where both angles are relative to the normal NOTE: not relative to the surface

law of reflection

### refraction is the bending of light upon entering a new medium

the bending of light upon entering a new medium

### the angle the transmitted ray makes with the normal is the angle of refraction

the angle that the transmitted ray makes with the normal

### index of refraction

value that indicates how much slower light will travel through a medium than empty space
NOTE: the larger this value is, the slower the light will travel through the medium

### n=1

index of refraction for air

### n=c/v

Equation that relates velocity and index of refraction

### n₁sin(theta₁)=n₂sin(theta₂)

law of refraction equation (Snell's Law)

### the the ray is slowed and moved toward the normal, thus theta₂<theta₁

If the index of refraction is higher for the second medium than the first, what does this indicate about angle theta₂?

### the ray is accelerated and moved away from the normal, thus theta₂>theta₁

If the index of refraction is lower for the second medium than the first, what does this indicate about the angle theta₂

### total internal reflection

all the incident rays will be reflected back into the original medium, meaning there will be no refracted light rays
NOTE: will occur if theta is greater than critical angle

### sin(critical angle)=n₂/n₁ where n₁ is greater then n₂

critical angle for total internal reflection

### light will neither be reflected nor refracted, and skimmer across the surface

What occurs when the angle of incidence equals the critical angle?

### redistribution of a waves intensity is diffraction

redistribution of a waves intensity

### polarizated light is light in which the direction of polarization has been restricted somehow

light in which the direction of polarization has been restricted somehow

### light waves travelling through a material medium at different frequencies are dispersion

light waves traveling through a material medium that have different frequencies
NOTE: this is an exception to rule 1 of waves

### frequency will be inversely proportional for dispersion NOTE: violet light will travel the slowest and red light will travel the fastest

Different frequencies of EMR that disperse through a material medium display what relationship to velocity?

### a surface that forms an image by reflecting light is a mirror

surface that forms an image of an object by reflecting light

### plane mirror

mirror than forms a virtual image that is the same size as the object where the image appears to be as far behind the mirrors surface as the object is in front of it

### a concave mirror is thinnest in the middle and will reflect light toward the focal length

mirror that is thinnest in the middle, where light is reflected toward the focal length

### convex mirrors are thickest in the middle and will reflect light away from the focal length

mirror that is thickest in the middle, where light is reflected away from the focal length

### the focal length is half the distance to the center of curvature

half the distance to the center of curvature, or half the radius where rays of light intersect from above and below the axis

### 1. Where is the image? 2. Is the image real or virtual? 3. Is the image upright or inverted? 4. How tall is the image compared to the object?

4 questions to ask when looking at mirrors?

### real images have light rays that are actually focused at their position

light rays that actually focus at the position of the image and can be projected onto a surface

### virtual image

light rays that don't actually focus at the apparent location of the image, meaning no light intersects where the image forms

### 1/o(+/-)1/i=1/f i is the distance from mirror to the image o is the distance from the mirror to the object

the mirror/lens equation

### the image and focal length are on the same side as the observer

What does having both a positive f and i value indicate?

### negative i indicates the image is virtual

What does having negative i value indicate?

### m=-i/o NOTE: m gives the ratio of the height of the image to the height of the object

magnification equation

### a positive magnification value indicates the image is upright

What does a positive m-value indicate?

### a negative magnification indicates that the image is inverted

What does a negative m-value indicate?

### real images are inverted and virtual images are upright

Real images are (blank) and virtual images are (blank)

### a concave mirror reflects light down onto the focal length, therefore it will have a positive focal length

What is the value of the focal length for a concave mirror?

### a convex mirror reflects light away from the focal length, and therefore has a negative focal length

What is the value of the focal length for a convex mirror?

### lens

a thin piece of clear glass or plastic that forms an image of an object by refracting light

### converging (convex) lens

lens that is thicker in the middle than it is at the ends, so it refracts lights toward the axis

### a lens that is thinner in the middle than it is at the ends is a diverging lens

lens that is thinner in the middle than it is at the ends, so it refracts light away from the axis

### a focal length for a converging lens will be positive b/c refracted rays are toward the axis

What is the value of the focal length for a converging lens?

### the diverging len will refract light away from the axis, and therefore have a negative focal length

What is the value of the focal length for a diverging lens?

### power of a lens is the reciprocal of the focal length is diopters

the reciprocal of the focal length measured in diopters

### myopia is where the focal length lies in front of retina

term for nearsightedness, where the lens refracts the incoming light to a focal length that is too short, or in front of the retina

### hyperopia

term for farsightedness, where the lens refracts incoming light to a focal length that is too long, or behind the retina

### accommodation

the ability to focus on nearby objects through the action of ciliary muscles, which squeeze the lens to increase its curvature and shorten the focal length

### use a diverging lens that has a negative focal length value to extend the focal length further back

How to correct myopia?

### use a converging lens that has a positive focal length value to shorten the focal length

How to correct hyperopia?

### the radius of curvature. focal length is half the radius of curvature, so if it changes, so must the focal length

What is the only thing that can change the focal length?

### If the lens or mirror has a negative focal length, subtract the two distances. If the focal length if positive, add the two distances

using the lens equation, how does the type of lens or mirror affect the sign?