Light and Optics

Question 1

List the waves in order of increasing wavelength(short to long)

Answer 1

Radio waves.. Microwaves.. Infrared.. Visible light.. UV.. Xray.. Gamma rays

Question 2

What is the visible light spectrum?

Answer 2

700nm - 400nm(ROYGBV)

Question 3

What is the relationship between color perceived and the wavelength

Answer 3

Color perceived is the wavelength emitted(ex. for green plant, red light and blue light wavelength are absorbed for growth and green wavelength is emitted)

Question 4

What is the eq for speed of light relating to f and λ?

Answer 4

c = fλ; c = 3 x 10^8m/s

Question 5

What is Reflection?

Answer 5

Light ray is bouncing off, not absorbed into the 2nd medium

Question 6

What is the Law of Reflection and its equation?

Answer 6

Θ1 = Θ2
The angle that the incident light hits the medium is the same as the angle reflected. All angles are measured from normal

Question 7

What are plane mirrors and their characteristics in forming an image?

Answer 7

image is formed behind the mirror and is virtual because there is no actual object behind the mirror. The image is formed because the light rays that are reflected off the object go to the plane mirrors and are also reflected off from the plane mirrors, which then are perceived by the eye. So the eye thinks there is an object behind the mirror NOT because of the actual light rays that are reflected off the object BUT because of the the light rays that are reflected off the mirrors which were reflected off the object(so two reflections) are perceived.

Question 8

What kind of image is formed by plane mirrors?
upright/inverted
Reduced/Enlarged/Same
Farther/Closer/Same

Answer 8

Upright
Same sized
Same distance
Flip Left and Right

Question 9

What are spherical mirrors and their characteristics in forming an image?

Answer 9

Concave and Convex
These mirrors have a radius that is twice as long as the focal point( f = r/2)
Concave mirrors: Converging
Convex mirrors: Diverging

Question 10

What is the eq used to find the focal length, image distance, object distance, and radius?(for Both spherical mirrors and plane mirrors)

Answer 10

1/f = 1/o + 1/i =2/r………….Spherical mirror(and all lenses)
1/o + 1/i = 0; f = r…………..Plane mirror

Question 11

What is magnification and the equation to obtain it?

Answer 11

Magnification is where the image is either bigger/smaller than the actual object.
m = -i/o

Question 12

Define the following: 
i  = positive:
i = negative:
m = positive:
m = negative:
|m| > 1 :
|m| < 1 : 
o = positive:
o = negative:
r = positive:
r = negative:
f = positive:
f = negative =

Answer 12

Real image
Virtual image
Upright image
Inverted image
Enlarged
Reduced
object in front of mirror
object behind the mirror
Concave mirror
Convex mirror
Concave mirror
Convex mirror

Question 13

What are the three rays that should be considered when solving optical questions?

Answer 13

1 ray parallel to axis, reflects off to F(focal point) and goes through it
1 ray through F, reflects off mirror in parallel
1 ray reflects at the intersect of the axis and parallel w/ the ray that went parallel from the object and is reflecting off the mirror in angle

Question 14

What are the three cases for concave mirrors their characteristics?

Answer 14

1) object behind F…inverted, real, enlarged image
2) object on F…no image due to parallel rays
3) object in front of F …upright, virtual image

Question 15

When will the image be seen and when will the image not be seen?

Answer 15

seen: when and where two rays intersect

not seen: when two rays do not meet and are parallel

Question 16

How are the images different in Concave and Convex mirrors?

Answer 16

in convex mirrors, the image is always virtual, upright, reduced image.

Question 17

What is Refraction

Answer 17

Bending of light as it passes through medium 1 to 2 and changes speed

Question 18

What are the two Snell’s law?

Answer 18

1) n = c/v ;
n: index of refraction of the medium,
c: speed of light in vacuum
v: speed of light in medium

2) n1 sin Θ1 = n2 sin Θ2
Θ: angle is measured from normal

Question 19

What is the relationship between different mediums and the refracted angles?

Answer 19

If light goes from high ‘n’ to low ‘n’, refracted angle Θ2 bends away from normal
If light goes from low ‘n’ to high ‘n’, refracted light bends toward normal

Question 20

What is Total internal reflection?

Answer 20

When n1 > n2(high to low), refracted angle > incident angle( Θ2 > Θ1). As incident angle increases, the refracted angle will eventually reach 90 degrees, meaning the light ray will pass through both mediums(critical angle). After this point, there will be no refracting, but only Reflection.

Question 21

What’s the eq to get Θc?

Answer 21

Θc = inv sin[n2/n1]

Question 22

What are the two differences between mirrors and lenses?

Answer 22

• mirrors reflect, lenses refract.
• they use the same eq for image distance
• there is one focal point for mirrors, two for lenses(one behind and in front of lenses)
• Concave mirrors and Convex lenses are converging
• Convex mirrors and Concave lenses are diverging

Question 23

What is the eq to find the Focal point of a real lens?

Answer 23

1/f = (n-1) [1/r1 - 1/r2]

r1: 1st curvature
r2: 2nd curvature

Question 24

What is the “Real side” and how does it differ between mirrors and lenses?

Answer 24

Real side is the side where light goes after interacting with Optics(either mirror/lens)
Mirrors: Real side is the same side as the object
Lens: Real side is the opposite side of object
Virtual side is the opposite of the Real side

Question 25

What is Spherical aberration?

Answer 25

Blurring of the Periphery of the image because Spherical mirrors/lenses are not perfect

Question 26

How is power measured in Optics?

Answer 26

P = 1/f

Question 27

How does the focal point of multiple lens system behave and what is its equation?

Answer 27

1/f = 1/f1 + 1/f2 + 1/f3…

acts as negligible distances

Question 28

How does the Power of multiple lens system behave?

Answer 28

P = P1 + P2 + P3…

Additive

Question 29

How does the magnification behave in multiple lens system?

Answer 29

m = m1 x m2 x m3…

Question 30

What is Diffraction?

Answer 30

Spreading out of light as it passes through a narrow opening

Question 31

What does the slit do when light passes through it?

Answer 31

Narrow slit allows the light to spread out. narrower slit = more spread out

Question 32

What is slit-lens system?

Answer 32

Light -> slit -> lens -> screen
Lens is placed between slit and screen because spread-out light rays can align linearly to the screen which we want to observe. This system gives a specific pattern of one brightest fringe in the middle, and alternating bright and black fringes to the both side. Maximum(in the center) is 2x wider than the other ones.

Question 33

How to calculate the location of the dark fringes in a single slit system?

Answer 33

a sin θ = nλ
a: width of the slit
λ: wavelength of incident light
 θ: angle between axis and dark fringe
n: integer for number of fringe

Question 34

What is the Young experiment?

Answer 34

Light -> Lens -> Double slit plate -> screen

This showed that light has wave functions and can form interference. Contructive: brighter, Destructive: darker

Question 35

How to calculate the position of dark fringes in a multiple slits system?

Answer 35

d sin θ = (n + 1/2)λ

Question 36

What is plane-polarized light?

Answer 36

light w/ wave that oscillates along a single plane(x, y, or z).

Question 37

What is the difference between polarized light and unpolarized light?

Answer 37

unpolarized light oscillates in random orientation, but polarized light only oscillates in certain planes.

Question 38

Polarization is organizing what?

Answer 38

electricfield vectors of light

Question 39

What is circular polarization?

Answer 39

light wave that has the same amplitude and propagates by rotating clockwise or counter clockwise.