Normal Line Incident RayReflected Ray
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Transcript of Normal Line Incident RayReflected Ray
Light & Optics Review
Normal Line
Terminology of Reflection
Incident Ray Reflected Ray
<i <r
<i = <r
1. <i is equal to <r
2. Incident ray, reflected ray and the normal all lie in the same plane.
Laws of Reflection
Mirror
Locating an image in Mirror
Size Smaller vs. Same vs. Larger
Attitude Upright vs. Inverted
Location Where the image is located
Type Real vs. Virtual
SALT
Incident rays entering to a “Cave” Concave = converging
Concave Mirrors - Rules
C VF
Principal axis
Image on SAME SIDE as object = REAL Image behind the mirror = VIRTUAL
Concave Mirrors – Real vs. Virtual Image
Object
REAL Image
VIRTUALImage
Simply use 2 of the rules
Concave Mirrors – Finding the Image
C VF
If object is at F = no clear image
Concave Mirrors – Finding the Image
F VC
Lines do not meet up
If object is between F and V = Virtual image
Concave Mirrors – Finding the Image
F VC
Incident rays”bouncing off a ball” Convex = diverging
Convex Mirrors - Rules
V F
Principal axis
C
Incident rays ”bouncing off a ball” Image is ALWAYS smaller and virtual
Convex Mirrors – Finding the Image
V F C
Bending of light when it travels from one medium to anotherIf SLOWING down when entering another medium
bend TOWARDS the normal
Normal LineIncident Ray <i
Medium A (Faster\)
Medium B (Slower) <R Refracted Ray
Refraction
If SPEEDING UP when entering the medium bend AWAY from the normal
Normal LineIncident Ray <i
Medium A (Slower)
Medium B (Faster)
<R Refracted Ray
Refraction
Either use: n = c . OR n = sin <i . v sin <R Example 1: Speed of light in air is 3.00 x 108 m/s. Speed of
light in salt is 1.96 x 108 m/s. Light enters from air to salt. Which way does the light bend? What is the index of refraction?
Calculating Index of Refraction (n)
Either use: n = c . OR n = sin <i v sin <R Example 2: Index of refraction of quartz is 1.46. If the angle
of incident ray from air is 600, what is the angle of refracted ray in quartz?
Calculating Index of Refraction (n)
ONLY occurs under 2 conditions:
1. Light is travelling more slowly in 1st medium than in 2nd medium (going from SLOWER to FASTER)
2. Angle of incidence is GREATER than critical angle
Total Internal Refraction
Normal Line
Air (FASTER)
Water (SLOWER)
Total Internal Refraction
Critical angle
F = principal focus F’ = secondary principal focus O = optical centre
Converging Lens - Rules
F’ 2FF
Principal axis
2F’ O
If Image is on the OPPOSITE SIDE of the lens from the object = REAL Image
If Image is on the SAME SIDE as object = Virtual Image
Converging Lens – Real vs. Virtual Image
REAL Image
ObjectVIRTUAL Image
Simply use 2 of the rules
Converging Lens – Finding the image
F’ 2FF2F’ O
The only time you’ll get VIRTUAL image with converging lens is when the object is between F’ and O
Converging Lens – Finding the image
F’ 2FF2F’ O
F = principal focusF’ = secondary principal focusO = optical centre
Diverging Lens- Rules
F 2F’F’
Principal axis
2F O
Always the SAME image characteristics no matter where the object is located: Smaller, upright, virtual, same side as object.
Diverging Lens- Finding the image
F 2F’F’
Principal axis
2F O
1 + 1 = 1
do di f
Object
Thin Lens Equation
F’ 2FF2F’ O
Image
do
f f
di
ho
hi
1 + 1 = 1do di f
do is always +
di is + for real image
- for virtual image
f is + for converging lens
- for diverging lens
Thin Lens Equation
M = hi = - di
ho do
h0 and h1 are:
+ when measured upward - when measured
downward
M is: + for upright image - for inverted image