File slide. teoriOptka

(1)

Cahaya/Optik

(2)

Introduction

• Cahaya adalah gelombang yang memindahkan tenaga tanpa perambatan massa.

• Di dalam ruang hampa warna –warna mempunyai

kecepatan perambatan yang sama, tetapi frekuensi dan panjang gelombang masing-masing warna berbeda-beda

• Cahaya merupakan gelombang transversal yang termasuk gelombang elektromagnetik.

(3)

Sifat-sifat Gelombang Elektromagnetik

1. Gelombang elektromagnetik dapat merambat

dalam ruang tanpa medium

2. Merupakan gelombang transversal

3. Tidak memiliki muatan listrik sehingga bergerak

lurus dalam medan magnet maupun medan

listrik

4. Perubahan medan listrik dan medan magnet

(4)

(5)

(6)

(7)

Sifat Cahaya

•

Dapat mengalami pemantulan (refleksi)

•

Dapat mengalami pembiasan (refraksi)

•

Dapat mengalami pelenturan (difraksi)

•

Dapat dijumlahkan (interferensi)

•

Dapat diuraikan (dispersi)

•

Dapat diserap arah getarnya (polarisasi)

(8)

(9)

(10)

Law of Reflection

The angle of

incidence equals

the angle of

reflection.

The incident ray

strikes the mirror.

(11)

Refraction

• Light rays may bend as they cross a boundary from one material to another, like from air to water.

• This bending of light rays is known as refraction.

(12)

Refraction

When a ray of light crosses from one material to another, the amount it bends depends on the difference in index of

(13)

Index of refraction

The ability of a material to bend rays of light is described by the

(14)

(15)

Snell's law of refraction

n

_i

sin

Q

_i

= n

_r

sin

Q

_r

Index of refraction of

refractive material Angle of incidence

(degrees)

Angle of refraction (degrees)

Index of refraction of

(16)

(17)

Dispersion

•

When white light passes through a glass prism, blue

is bent more than red.

(18)

Dispersion

• The variation in refractive index with color is called

dispersion.

• A rainbow is an example of dispersion in nature.

• Tiny rain droplets act as

(19)

Mirrors, Lenses, and Images

(20)

Mirrors, Lenses, and Images

•

Objects are real physical

things that give off or

reflect light rays.

•

Images

are pictures of

objects that are formed

in space where light

(21)

(22)

(23)

(24)

(25)

LASER

•

L

ight

A

mplification by

S

timulated

E

mission

of

R

adiation

•

Emits very intense,

monochromatic

light at

high power (intensity)

•

All waves

in phase

(unique), and parallel

(26)

(27)

(28)

Spontaneous:

Incoherent radiation

Differs in direction and phase

Advantages of Laser

• Low Beam Divergence (“Small

dot”)

• Nearly Monochromatic (“narrow

bandwidth”)

• Coherent (“constructive

(29)

(30)

(31)

(32)

(33)

(34)

Candela,

(35)

(36)