Welcome to PHYSICS –I (PH10001) Sir Isaac Newton Thomas Young Christiaan Huygens Welcome to PHYSICS –I (PH10001) Werner Heisenberg Niels Bohr Albert Einstein

Course Content Oscillations – 8 lectures Waves - 8 lectures   Waves - 8 lectures Interference - 7 lectures Diffraction - 7 lectures Polarisation - 4 lectures Quantum Physics - 8 lectures L-T-P 3-1-0

Instructor: Dr. Anushree Roy Contact number : 83856 Availability : Venue: Room No. C133 in main building Time : Thursday 5.00-6.30 pm Slides other details available at: www.webteam.iitkgp.ernet.in/physics1

Class Timings Monday: From 1.30 to 2.30 (door will close at 1.40)   Tuesday: From 3.30 to 5.30 (door will close at 3.45)

Marks Break-up Mid semester exam: 30 End semester exam: 50 Tutorial: 20   www.webteam.iitkgp.ernet.in/physics1

BOOKS FEYNMAN LECTURES ON PHYSICS VOL I THE PHYSICS OF VIBRATIONS AND WAVES by H. J. PAIN FUNDAMENTALS OF OPTICS by JENKINS AND WHITE OPTICS by EUGENE HECHT

1. LECTURE NOTES & PROBLEMS BANK for PHYSICS by SARASWAT AND SASTRY 2. PHYSICS I: OSCILLATIONS AND WAVES by BHARADWAJ AND KHASTAGIR 3. LECTURE NOTE S AND PROBLEMS BANK by SAYAN KAR at http://www.cts.iitkgp.ernet.in/Phy_1st/tut.html Audio lecture: www.webteam.iitkgp.ernet.in/physics1

Discussion Forum https://www.facebook.com/groups/523462897801020/

OSCILLATION HARMONIC OSCILLATION

OSCILLATION

SPRING SIMPLE HARMONIC MOTION Assumption : spring is perfectly linear force of pulling back  restoring force -x HOOKE’S LAW m x m m max Equation of motion m x max k : stiffness constant

Second order ordinary homogenous linear differential eqn. second order: because the highest derivative is second order. ordinary: because the derivatives are only with respect to one variable (t). homogeneous: because x or its derivatives appear in every term, and linear: because x and its derivatives appear separately and linearly in each term

One of the solutions of the differential equation A is a constant : Amplitude of motion wo refers to natural motion the spring

Velocity : Acceleration :

Oscillation! For A=1

Physical significance of A A is amplitude of motion Time pattern of the motion is independent A

Physical significance of w0 Motion repeats when changes by 2p : Phase of the motion

T: Time period of motion

Phase estimation For black curve For red curve

Shifting the beginning (origin) of the time General solution t1 = some constant Form

w0: angular freq. (amount of phase change in 1 sec) (w0t+f) : phase of the oscillation f: phase shift from some defined origin of time

Estimating Amplitude and Phase from Initial conditions Initial conditions to determine D and E At t =0 x=x0 and v=v0 Hence find amplitude and phase

Velocity : Acceleration :

Potential energy of the spring-mass system

Kinetic energy of the spring-mass system

Total energy of the spring-mass system Total energy = K.E + P.E

Simple Pendulum Assumption : massless unstretchable string q l g m

Harmonic and circular motion (only an Analogy) v Acceleration (a)  R q X Geometrically x component of the displacement of a particle moving along a circular path with uniform speed is a SHM

Summary Every oscillatory motion or periodic motion has a frequency w=2pf Unit of f : 1Hertz = 1Hz = 1 oscillation/sec =1sec-1 The period T is the time required for one complete oscillation or cycle Displacement during SHM as a function of time xmax: amplitude

xmax=A Velocity during SHM as a function of time wxmax: velocity amplitude xmax=A Acceleration during SHM as a function of time w2xmax: acceleration amplitude

Reference FEYNMAN LECTURES ON PHYSICS VOL I Author : RICHARD P FEYNMAN, IIT KGP Central Library : Class no.  530.4