mk fisika dasar 2_bab15
TRANSCRIPT
![Page 1: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/1.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 1/44
MK FISIKA DASAR 2ENGE600004
4 SKS
Rachmat Andika
Multiferroic Research Group
Departemen FisikaFMIPA - UI
![Page 2: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/2.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 2/44
THE NATURE OF LIGHT AND
THE LAWS OF
GEOMETRIC OPTICS
![Page 3: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/3.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 3/44
MATERI
The Nature of Light
Dualism of Light
The Speed of Light
Reflection and Refraction Total Internal Reflection
Dispersion
Huygens’s Principle
Fermat’s Principle
![Page 4: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/4.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 4/44
THE NATURE OF LIGHT
The light can propagate in a vacuum media
The light has a wave properties, such as Reflection
Refraction
In seeing something, the light has an important role
for our eyes
A rainbow is one of the product of light that dispersed
by rain/ water
![Page 5: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/5.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 5/44
HISTORICAL OF LIGHT
Newton Light was considered to be a stream of particles that was emitted by
the object
He could explain reflection and refraction
Huygens (1678) Wave theory could also explain reflection and refraction
Young (1801) Light rays interfere with each other and it couldn’t be explained by a
particle theory
Maxwell Light was a form of high-frequency electromagnetic waves
![Page 6: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/6.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 6/44
BUT ….
They could not explain some subsequent experiments,
such as
Where the constant of proportionality h = 6.63 x 10-34 Js
Photoelectric Effect
Max Planck (1900) → Einstein (1905)
The quantization model assumes that the energy of a
light wave is present in particles called photons
Is light a wave or
particle?
![Page 7: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/7.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 7/44
THE RAY APPROXIMATION IN
GEOMETRIC OPTICS
In the ray approximation, we assume that a wave moving through a
medium travels in a straight line in the direction of its rays
λ >> d, the rays continue in a straight-line path, and the ray
approximation remains valid
λ ≈ d, the rays spread out after passing through the opening λ << d, the opening behaves as a point source emitting spherical
waves
![Page 8: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/8.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 8/44
WAVE FRONT
To simplify light as a wave
Wave front is every point on wave crest
![Page 9: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/9.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 9/44
REFLECTION
The direction of a reflected ray is in the plane
perpendicular to the reflecting surface that contains the
incident ray
Specular reflection on a
smooth surface
diffuse reflection on a
rough surface
![Page 10: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/10.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 10/44
LAW OF REFLECTION
![Page 11: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/11.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 11/44
THE DIFFERENT BETWEEN
REFLECTIONS
For diffuse reflection, the eyes could see the light
reflection on all angles
For specular reflection, the eyes should have to
on the right position with respect to the light
![Page 12: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/12.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 12/44
EXAMPLE
Two mirrors make an angle of 120o with each other. A
ray is incident on mirror M1 at an angle 65o to the
normal. Find the direction of the ray after it is
reflected from mirror M2?
![Page 13: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/13.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 13/44
REFRACTION
When a ray of light traveling through a transparent
medium encounters a boundary leading into another
transparent medium,part of energy isreflected andpart
enters the second medium
The ray that enters the secondmedium is bent at the boundary
A basic definition of refracted
![Page 14: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/14.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 14/44
(a) The light is bent toward the normal
(b)
The light is bent away from the normal
![Page 15: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/15.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 15/44
INDEX OF REFRACTION
In general, the speed of light in any material is less than its
speed in vacuum.
In fact, light travels at its maximum speed in vacuum.
Index of refraction is a dimensionless number greater than unity Becausev is always less thanc.
n is equal to unity for vacuum
![Page 16: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/16.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 16/44
SNELL’S LAW OF REFRACTION
As light travels from one medium to
another, its frequency does not change
but its wavelength
![Page 17: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/17.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 17/44
![Page 18: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/18.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 18/44
EXAMPLE
A beam of light of wavelength 550 nm traveling in air
is incident on a slab of transparent material. The
incident beam makes an angle of 40.0o with the
normal, and the refracted beam makes an angle of
26.0o
with the normal. Find the index of refraction of the material
![Page 19: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/19.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 19/44
EXAMPLE
A light ray of wavelength 589 nm traveling through
air is incident on a smooth, flat slab of crown glass at
an angle of 30.0o to the normal Find the angle of refraction
![Page 20: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/20.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 20/44
EXAMPLE
A laser in a compact disc player generates light that
has a wavelength of 780 nm in air. Find the speed of this light once it enters the plastic of a
compact disc (n = 1.55)
What is the wavelength of this light in the plastic
![Page 21: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/21.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 21/44
Angle of deviation
![Page 22: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/22.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 22/44
HUYGEN’S
PRINCIPLE
All points on a given wave front are taken as point sources for theproduction of spherical secondary waves, calledwavelets, which
propagate outward through a medium with speeds characteristics of
waves in that medium.
After some time interval has passed, the new position of the wave front
is the surface tangent to the wavelets
![Page 23: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/23.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 23/44
DISPERSION AND PRISMS
Index of refraction varies with the wavelength of the light passing
through the material. “ Dispersion”
Snell’s law of refraction indicates that light of different wavelength isbent atdifferent angles when incident on a refracting material.
Angle of deviation is an angle between a ray of single wavelength
incident on the prism from the left emerges refracted from its original
direction of travel
Angle of
deviation
![Page 24: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/24.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 24/44
Visible spectrum
![Page 25: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/25.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 25/44
![Page 26: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/26.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 26/44
MEASURING INDEX OF
REFRACTION USING A PRISM
![Page 27: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/27.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 27/44
TOTAL INTERNAL REFLECTION
Total internal reflection can occur when light is
directed from a medium having a given index of
refraction toward one having alower index of
refraction
θc : critical angle
The refracted light ray
moves parallel to the
boundary, θ2 = 90o
![Page 28: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/28.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 28/44
EXAMPLE
Find the critical angle for an air-water boundary
![Page 29: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/29.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 29/44
FERMAT’S PRINCIPLE
Fermat’s principle states that when a light ray travels
between any two points, its path is the one that requiresthe smallest time interval
PIERRE DE FERMAT(1601-1665)
![Page 30: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/30.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 30/44
IMAGE FORMATION
![Page 31: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/31.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 31/44
MATERI
Images formed by flat mirrors
Images formed by spherical mirrors
Images formed by refraction
Thin LensesLens Aberrations
Optics Systems
![Page 32: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/32.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 32/44
IMAGES FORMED BY FLAT MIRRORS
Images are classified as areal orvirtual
A real image is formed when light rays pass through and diverge from
the image point
A virtual image is formed when the light rays do not pass through theimage point but only appear to diverge from that point
the image of an object seen in a
flat mirror isalways virtual
![Page 33: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/33.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 33/44
The image is as far behind the mirror as the object isin front
The image is unmagnified, virtual, and upright
The image has front-back reversal
![Page 34: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/34.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 34/44
IMAGES FORMED BY SPHERICAL
MIRRORS
Concave mirror Mirror, in which light is reflected from the inner, concave
surface
Concave mirror is sometimes called aconverging mirror,
because the rays from any point on an object converge after
reflection
![Page 35: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/35.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 35/44
IMAGES FORMED BY SPHERICAL
MIRRORS
Convex mirror Mirror, in which light is reflected from the outer, convex
surface
Convex mirror is sometimes called adiverging mirror,
because the rays from any point on an object diverge after
reflection
![Page 36: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/36.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 36/44
MIRROR EQUATION
fis focal length,
fis usually not the point at which the light rays focus to form an image.the focal point is determined by the curvature of the mirror
It doesn’t depend on the location of the object at all
Or doesn’t depend on the material of mirror
But it is different for lenses
The light actually passes through the
material and the focal length depends on the
type of material of the lens
![Page 37: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/37.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 37/44
RAY DIAGRAMS FOR MIRRORS
![Page 38: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/38.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 38/44
RAY DIAGRAM OF CONCAVE
MIRRORS
![Page 39: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/39.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 39/44
RAY DIAGRAM OF CONVEX MIRRORS
![Page 40: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/40.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 40/44
THIN LENSES
Lens makers’ equation
Lenses are used to form images by refraction
in optical instruments, such as cameras,
telescopes, and microscopes
![Page 41: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/41.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 41/44
RAY DIAGRAM FOR THIN LENSES
![Page 42: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/42.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 42/44
![Page 43: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/43.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 43/44
EXERCISE
Two thin converging lenses of focal lengths f1 = 10 cm
and f2 = 20 cm are separated by 20 cm. an object is
placed 30 cm to the left of lens 1. Find the position
and the magnification of the final image.
![Page 44: MK Fisika Dasar 2_Bab15](https://reader033.vdocuments.site/reader033/viewer/2022050807/5695cff21a28ab9b02903c9c/html5/thumbnails/44.jpg)
7/23/2019 MK Fisika Dasar 2_Bab15
http://slidepdf.com/reader/full/mk-fisika-dasar-2bab15 44/44