gelombang optik 1 - gelombang pada tali.ppt

MK. Gelombang & OptikMK. Gelombang & Optik

Teknik Mesin

Fakultas Teknik Universitas Indonesia Semester PTA 2007/2008

Dwi Seno Kuncoro Sihono, M.SiDwi Seno Kuncoro Sihono, M.SiWebsite: dwiseno.fisika.ui.eduWebsite: dwiseno.fisika.ui.edu

Email: dwiseno@fisika.ui.ac.idEmail: dwiseno@fisika.ui.ac.id

HP: 021-93399802, 08129988702HP: 021-93399802, 08129988702

Silabus Mata Kuliah Silabus Mata Kuliah Gelombang & Optik (2 sks)Gelombang & Optik (2 sks)

Tujuan

Memahami konsep-konsep dan hukum-hukum dasar Fisika Gelombang & Optik dan menerapkannya dalam pemecahan persoalan gejala gelombang alami maupun gelombang yang timbul akibat teknis secara sistimatik dan ilmiah

Buku dan ReferensiBuku dan Referensi

D. Halliday dan R.Resnick, Fisika I + II, Terjemahan Erlangga

Ganijanti, A.S, Gelombang & Optik, Jurusan Fisika FMIPA-UI

Giancolli D.C., General Physics, Prentice Hall

Tipler, Fisika untuk Sains & Teknik, Terjemahan Erlangga.

dan Iain-Iain.

Evaluasi Evaluasi

Ujian Tengah Semester 40% Ujian Akhir Semester 40% Kuis , Tugas dan Absen 20%

JadwalJadwal

Kuliah Senin Pukul 08.00 – 09.50 Ruang K.210

Responsi Kamis Pukul 15.00 – 16.50 diganti 13.00 – 14.50 Ruang K.210 diganti (tentative)

SilabusSilabus

Minggu Pokok bahasan dan Isi pokok bahasan

1Gelombang: Definisi dan fungsi gelombang, macam-macam gelombang

2Bunyi: Gelombang tekanan, gelombang kerapatan, gelombang simpangan, cepat rambat bunyi, Audiogram

3 Superposisi dan Gelombang berdiri

4 Cahaya

5

Polarisasi: pengertian dan uraian matematis Polarisasi linear, melingkar dan eliptis Gelombang pada perbatasan dua media Persamaan Fresnel dan Interpretasi

6 Derajat polarisasi, Bias rangkap dan Aktivitas aktif

7 Persiapan Ujian Tengah Semester

SilabusSilabus

Minggu Pokok bahasan dan Isi pokok bahasan

8Interferensi: Pengertian koherensi, Percobaan Young dan modifikasinya

9 Interferensi pada film tipis dan Gelombang diam

10Difraksi: pengertian difraksi Difraksi oleh 1 celah, Difraksi oleh 1 lubang, Difraksi oleh 2 celah dan Difraksi kisi

11Batas resolusi, daya pisahDifraksi Fresnel Difraksi Sinar-X oleh kristal

12Optika geometri, pantulan, pembiasan oleh permukaan 2 media datar, steris

13 Lensa : Alat-alat optik, Deviasi dan dispersi dan Fotometri

14 Persiapan UAS

GelombangGelombang

Getaran / gangguan / energi yang menjalar. Perpindahan energi dan momentum dari satu

titik di dalam ruang ke titik lain tanpa perpindahan materi

• Berdasarkan arah rambat gelombang : Gelombang Longitudinal Gelombang Transversal

• Berdasarkan sifat terjadinya gelombang Gelombang Elastis Gelombang Permukaan Gelombang Mekanik Gelombang Elektromagnet

The rich sound of a piano is due to waves on strings that are under tension. Many such strings can be seen in this photograph. Waves also travel on the soundboard, which is visible below the strings. In this chapter, we study the fundamental principles of wave phenomena.

Wave Wave MotionMotion

All mechanical waves require some source of disturbance a medium that can be disturbed some physical mechanism through which elements of the medium can influence each

other.

Propagation of a DisturbancePropagation of a Disturbance

Pulse traveling to the right

Pulse traveling to the left

vtxftxy ,

Persamaan gelombang berjalanPersamaan gelombang berjalan

vtxftxy ,

soalsoal

Sebuah pulsa bergerak memenuhi persamaan

tentukanlah Arah gerak, cepat rambat,

amplitudo

13

2, 2

tx

txy

Gelombang SinusoidalGelombang Sinusoidal

The wavelength () is the minimum distance between any two identical points (such as the crests) on adjacent waves m

The period (T) is the time interval required for two identical points (such as the crests) of adjacent waves to pass by a point. s

The frequency of a periodic wave (f) is the number of crests (or troughs, or any other point on the wave) that pass a given point in a unit time interval. hertz

Gelombang sinusoidalGelombang sinusoidal

0

2sin,

vtxAtxy

tkxAdt

dva

tkxAdt

dyv

yy

y

sin

cos

2

Gelombang SinusoidalGelombang Sinusoidal

A sinusoidal wave traveling in the positive x direction has an amplitude of 15.0 cm, a wavelength of 40.0 cm, and a frequency of 8.00 Hz. The vertical position of an element of the medium at t = 0 and x = 0 is also 15.0 cm Find the wave number k, period T, angular

frequency, and speed v of the wave. Determine the phase constant , and write a

general expression for the wave function.

Persamaan Differensial GelombangPersamaan Differensial Gelombang

2

2

2

22

t

y

x

yv

This expression applies in general to various types of traveling waves. For waves on strings, y represents the vertical position of elements of the string. For sound waves, y corresponds to longitudinal position of elements of air from equilibrium or variations in either the pressure or the density of the gas through which the sound waves are propagating. In the case of electromagnetic waves, y corresponds to electric or magnetic field components.

Persamaan Differensial GelombangPersamaan Differensial Gelombang

2

2

2

22

t

y

x

yv

Contoh : gelombang transversal tali

dxdx

yTdx

x

y

xTF

dxtgx

TF

y

y

2

2

2

2

dt

ydxmaF yy

2

2

2

2

dx

yT

dt

y

Tv

Persamaan Differensial GelombangPersamaan Differensial Gelombang

Refleksi dan TransmisiRefleksi dan Transmisi

Sefase Berbalik fase

when a wave or pulse travels from medium A to medium B and vA > vB (that is, when B is denser than A), it is inverted upon reflection. When a wave or pulse travels from medium A to medium B and vA < vB (that is, when A is denser than B), it is not inverted upon reflection.

Laju energi pada gelombang tali adalah banyaknya energi yang dialirkan melalui gelombang persatuan waktu

Daya, watt

vAP 2221

Laju EnergiLaju Energi

An 80.0-kg hiker is trapped on a mountain ledge following a storm. A helicopter rescues the hiker by hovering above him and lowering a cable to him. The mass of the cable is 8.00 kg, and its length is 15.0 m. A chair of mass 70.0 kg is attached to the end of the cable. The hiker attaches himself to the chair, and the helicopter then accelerates upward. Terrified by hanging from the cable in midair, the hiker tries to signal the pilot by sending transverse pulses up the cable. A pulse takes 0.250 s to travel the length of the cable. What is the acceleration of the helicopter?

Sebuah gelombang sinusoida yang kontinyu berjalan pada sebuah tali dengan kecepatan 80 cm/s. Pergeseran dari pertikel2 di x = 10 cm didapatkan berubah dengan waktu menurut persamaan y = 5 sin (1 – 4t). Massa jenis linier tali 4 g/cm, tentukanlah

Frekuensi, panjang gelombang Persamaan umum gelombang tersebut Tegangan tali

Latihan SoalLatihan Soal