Physics Lab Manual - KIT

KIT- KALAIGNARKARUNANIDHI INSTITUTE OF TECHNOLOGY Kannampalayam Post, Coimbatore – 641 402 (Approved by AICTE & Affiliated to Anna University, Chennai) DEPARTMENT OF PHYSICS PHYSICS LA...

KIT- KALAIGNARKARUNANIDHI INSTITUTE OF TECHNOLOGY Kannampalayam Post, Coimbatore – 641 402 (Approved by AICTE & Affiliated to Anna University, Chennai) DEPARTMENT OF PHYSICS PHYSICS LABORATORY MANUAL FOR FIRST SEMESTER B.E./B.Tech STUDENTS (Common to all branches) WEEK WEEK 1 WEEK 2 WEEK 3 WEEK 4 WEEK 5 WEEK 6 GROUP NO 1 EX NO 1 EX NO 2 EX NO 3 EX NO 4 EX NO 5 EX NO 6 2 EX NO 2 EX NO 3 EX NO 4 EX NO 5 EX NO 6 EX NO 1 3 EX NO 3 EX NO 4 EX NO 5 EX NO 6 EX NO 1 EX NO 2 4 EX NO 4 EX NO 5 EX NO 6 EX NO 1 EX NO 2 EX NO 3 5 EX NO 5 EX NO 6 EX NO 1 EX NO 2 EX NO 3 EX NO 4 6 EX NO 6 EX NO 1 EX NO 2 EX NO 3 EX NO 4 EX NO 5 1|P a ge  PHYSICS LABORATORY LIST OF EXPERIMENTS EX.NO NAME OF THE EXPERIMENTS Torsional pendulum-determination of moment of inertia of a disc and the rigidity modulus of a 1 wire. 2 Determination of Young’s modulus by uniform bending method 3 Determination of Young’s modulus by Non uniform bending method 4 Determination of thickness of a thin wire – Air wedge method (a) Determination of particle size using Laser. 5 (b) Determination of Wavelength using Laser (C) Determination of acceptance angle in an optical fiber. 6 Determination of specific resistance of a given coil of wire – Carey Foster’s Bridge 2|P a ge  1. Torsional Pendulum-Determination of Moment of Inertia of a disc and the Rigidity Modulus of a wire Aim To determine the Moment of Inertia of the disc and the Rigidity modulus of the material of a given wire by torsional oscillations. Apparatus required A meter scale, Circular metal disc, suspension wire, biscuit balance, slotted weights, stop watch, vernier calipers, screw gauge, etc. Formula (i) Moment of Inertia of the disc I= (MR2/2) Kg m2 (ii) Rigidity modulus of the material of the given wire n =(8∏IL/r4T2 ) Nm-2 Explanation of Symbols Symbol Explanation Unit M Mass of circular disc Kg R Radius of the circular disc Metre r Radius of the given wire Metre L Length of the suspension wire Metre T Time period for various lengths Second DIAGRAM 3|P a ge TABULATION (i) To find the period of oscillation(T) Length of the Time for 10 Time S.No. suspended oscillations T2 L/T2 period(T) wire(L) Trial-1 Trial-2 Mean Unit X 10-2m Sec Sec Sec Sec S2 ms-2 Mean= (ii) Measurement of the suspension wire using Screw gauge(r) Least Count= 0.01mm Zero error= ……div………mm Zero correction= ……div………mm Sl.No. PSR HSC OR Correct Reading = OR ± ZC Unit 10-3m div 10-3m 10-3m 1 2 3 4 Mean 4|P a ge  (iii) Measurement of the diameter of the disc using Vernier calipers(R ) Least Count= 0.01cm Sl.No. MSR VSC OR Correct Reading = OR ± ZC Unit 10-2m div 10-2m 10-2m 1 2 3 4 Mean Result (i) Moment of Inertia of the disc I =……….. Kg m2 (ii) Rigidity modulus of the material of given the wire (n) =…………Nm-2 2.Uniform Bending-determination of Young’s Modulus. Aim To determine the young’s modulus of the given material of the beam by uniform bending. Apparatus required A meter scale, travelling microscope, pin, slotted weights with hanger, vernier calipers, screw gauge, knife edges etc., 5|P a ge Formula The young’s modulus of the given material of the beam (i) By calculation Y = (3g al2/2bd3) (M /y) Nm-2 (ii) By Graphical method Y= (3g al2/2bd3) (1 /K) Nm-2 Symbol Explanation Unit g Acceleration due to gravity ms-2 l Distance between the two knife edges Metre b Breadth of the beam Metre d Thickness of the beam Metre y Depression produced for ‘M’ kg of load Metre M Load applied Kg K Slope y/M from graph mKg-1 Distance between the weight hanger and the a metre adjacent knife edge DIAGRAM 6|P a ge Tabulation (i) To find M/y LC= 0.001 cm. TR=MSR+ (VSCxLC) Distancebetween knife edges (l)= Microscope Readings S. Load Elevation Loading Unloading Mean M/y No (M) (y) MSR VSC TR1 MSR VSC TR2 -3 Unit 10 kg Cm Div cm Cm Div cm 10-2m Metre Kgm-1 1 W 2 W+50 3 W+100 4 W+150 5 W+200 6 W+250 (i) To find the thickness (d) of the beam using Screw gauge Least Count= 0.01mm Zero error= ……div……….mm Zero correction= ………div……….mm Sl.No. PSR HSC OR Correct Reading = OR ± ZC Unit 10-3m div 10-3m 10-3m 1 2 3 4 Mean 7|P a ge  (ii) To find the breadth (b) of the beam using vernier caliper Least Count=0.01cm Sl.No. MSR VSC OR Correct Reading = OR Unit 10-2m div 10-2m 10-2m 1 2 3 4 Mean Result The young’s modulus of the given material of the beam (i) By calculation Y = ……………….. Nm-2 (ii) By Graph Y = ……………….. Nm-2 3. NON-UNIFORM BENDING-DETERMINATION OF YOUNG’S MODULUS Aim To determine the young’s modulus of the given material of the beam by Non uniform bending. Apparatus required A metre scale, travelling microscope, pin, slotted weights with hanger, vernier calipers, screw gauge, knife edges etc., 8|P a ge Formula The young’s modulus of the given material of the beam (i) By calculation Y = (gl3/4bd3) * (M/y) Nm-2 (ii) By Graphical method Y= (gl3/4bd3) * (1/K) Nm-2 (from graph, 1/K= M/y) Symbol Explanation Unit g Acceleration due to gravity (g= 9.8) ms-2 l Distance between the two knife edges Metre b Breadth of the beam Metre d Thickness of the beam Metre y Depression produced for ‘M’ kg of load Metre M Load applied (M = 50x10-3) Kg K Slope y/M from graph m/Kg DIAGRAM 9|P a ge TABULATION (i) To find M/y LC= 0.001 cm TR=MSR+ (VSCxLC) Microscope Readings Depre Sl. Load Loading Unloading Mean ssion No. (M) MSR VSC TR1 MSR VSC TR2 (y) M/y -3 -2 -2 -2 -2 -2 Unit 10 kg 10 m Div 10 m 10 m Div 10 m 10 m Metre Kgm-1 1 W 2 W+50 3 W+100 4 W+150 5 W+200 6 W+250 (i) To find the thickness (d) of the beam using Screw gauge Least Count= 0.01mm Zero error = ……….div …………. mm Zero correction (ZC) = …….. div …………. mm Correct Reading = S.No. PSR HSC (OR=PSR+HSC X LC) OR ± ZC Unit 10-3m div 10-3m 10-3m 1 2 3 4 Mean 10 | P a g e  (ii) To find the breadth (b) of the beam using verinier caliper Z.E= Least Count= 0.01cm Z.C= Correct Reading = S.No. MSR VSC (OR=MSR+VSC X LC) OR ± ZC Unit 10-2m div 10-2m 10-2m 1 2 3 4 Mean Result The young’s modulus of the given material of the beam (i) By calculation Y = ……………….. Nm-2. (ii) By Graph Y = ……………….. Nm-2. 4. AIR WEDGE – DETERMINATION OF THICKNESS OF A THIN WIRE AIM To determine the thickness of a given thin wire (or) thin sheet of paper by forming interference fringes due to an air-wedge. APPARATUS REQUIRED: Travelling microscope, two optically plane glass plates, given wire (or) thin sheet of paper, sodium vapour lamp etc. 11 | P a g e FORMULA Thickness of the given wire (or) thin sheet of paper is given by lλ t= metre 2β Explanation of symbols Sl.No. Symbol Explanation Unit Distance between edge of contact and 1 l Metre the wire (or) paper Wavelength of the monochromatic 2 λ Metre source of light (5893 x 10-10m) 3 β Mean band width Metre DIAGRAM 12 | P a g e TABULATION (i) To find the band width (β) LC = 0.001 cm TR = MSR + (VSC X LC) Microscope Reading Width of Fringe Order of MSR VSC TR 10 Fringes width (β) the fringes X 10-2m Div. X 10-2m X 10-2m X 10-2m n n+5 n+10 n+15 n+20 n+25 n+30 n+35 n+40 n+45 n+50 Mean(β)= ii) To find the distance between the edge of contact and the material of wire (or) paper “l”. LC = 0.001 cm TR =MSR + (VSC X LC) Microscope Reading Position of the l =( R1~ R2) MSR VSC TR Microscope X 10-2m Div. X 10-2m X 10-2m At the edge of contact (R1) At the edge of material of wire (or) paper (R2) 13 | P a g e RESULT: The thickness of the given wire =………………………………… metr 5. (A) DEDERMINATION OF PARTICLE SIZE USING DIODE LASER AIM To determine the particle size of the given lycopodium powder using He-Ne laser source or diode laser. APPARATUS REQUIRED Laser source, Lycopodium powder, meter scale and screen. FORMULA  m D  Particle size a=   m  Rm  Where, m - Order of the ring. λ - Wave length of laser source (m) D - Distance between the glass plate and screen (m) Rm - Distance between the central bright point and nth dark fringe (m) Laser sourc e Fig. 1. Experimental setup for 14 | P a g e Particle size determination TABULATION (i) To find the size of the given particle Distance between Distance the central bright Particle size between Order of point and nth S.No. screen and diffraction fringe  m D  glass plate (m) a=   (Rm)  Rm  (D) Unit cm cm cm 1 2 1 3 1 2 2 3 1 2 3 3 Mean Wave length of laser source () = 690 nm = 690 x 10-9m RESULTS: The average size of the particle is ……………………meter 15 | P a g e  5(B). DETERMINATION OF WAVE LENGTH OF LASER USING GRATING AIM To determine the wavelength of the given laser source of light using grating. APPARATUS REQUIRED: He-Ne laser, grating, screen, paper and pencil. FORMULA Sinθ Wavelength of the given laser source, λ= m Nm Where, θ is the angle of diffraction (deg) m is the order of diffraction N is Number of lines in the grating per metre. (Lines / metre) λ is Wavelength of Known line. (m) DIAGRAM Laser source Grating Screen 16 | P a g e  (i) To find the wave length of the laser source. Readings of diffracted images Distance Order between Left side Right side Mean Sinθ Sl. of grating Tanθ1 Tanθ2 λ= θ=(θ1+ θ2)/2 Nm No. Diffra- and Xm Xm θ1 Xm Xm θ2 (deg) ction Screen D = = (m) (cm) D (deg) (cm) D (deg) (cm) (deg) (deg) RESULT: The wave length of the laser source is ………………………. m. 5. (C) DETERMINATION OF NUMERICAL APERTURE AND ACCEPTANCE ANGLE OF AN OPTICAL FIBRE AIM To determine the numerical aperture and the acceptance angle of an optical fiber. APPARATUS REQUIRED Laser light source, Laser power meter, Optical fibre cables of various Length, Optical fibre connectors, Numerical aperture and Mandrel for optical fibre. 17 | P a g e FORMULA: Numerical aperture = NA = n0 sin θa r Acceptance angle = θa = d Where, n0 = Refractive index of air=1 θa = Acceptance angle in radian r = radius of the circular image in metre d = Distance from the fibre end to circular image in metre. DIAGRAM Openin g Laser source Optical fibre Stand Screen Fig. 1. Experimental setup for Numerical Aperture 18 | P a g e  (i) Determination of Numerical Aperture and acceptance angle Distance from Radius of Acceptance the end to circular image Angle S.No circular image r r θa = d d NA = n0 sin θa (cm) (cm) (deg) 1 2 3 4 5 6 Mean RESULT: Numerical aperture of the optical fibre NA =………………………. Acceptance angle of the optical fibre a=……………………… 19 | P a g e  6.DETERMINATION OF SPECIFIC RESISTANCE OF GIVEN COIL OF WIRE-CAREY FOSTER’S BRIDGE Aim To determine the specific resistance of the given coil of wire by comparing two nearly equal resistances using a Carey-Foster Bridge. Apparatus required A Carey-Foster Bridge, Coil of the given wire, Leclanche cell (Bt), Key, two equal resistances P and Q, galvanometer, high resistance, jockey, resistance box, etc. Formula (i) Resistance of the given coil of wire X = [R+(l1-l2)rb] Ohm  X  r2  (ii) Specific resistance of the given coil of wire ρ =   Ω-m  l  Explanation of symbol Sl.No. Symbol Explanation Unit Resistance per metre length of the 1 rb Ω/m bridge = R/(l1-l2) 2 X Unknown resistance Ω 3 l1, l2 Balancing lengths metre 4 l Length of the given coil of wire metre Known value of resistance in the 5 R Ω resistance box 6 r Radius of the given coil of wire metre 7 X Unknown resistance Ω 20 | P a g e (i) Determination of Resistance per metre length of the bridge wire(rb) Resistance Balancing length Sl.No. induced in the rb = R / (l1~l2) l1 l2 box(R) Unit (Ω) 10-2 m 10-2 m Ω/cm Mean: 21 | P a g e  (ii) Determination of unknown resistance ( X) Balancing length Resistance With R in Sl.No. induced in the With R in the X =R + (l1- l2)rb the left gap box(R) left gap (l1) (l2) Unit (Ω) 10-2 m 10-2 m (Ω) Mean: (iii) To find the radius of the given coil of wire (r) LC = 0.01mm Zero error = ………. div……….. mm Zero correction = ………. div……….. mm Correct Reading = S.No. PSR HSC (OR=PSR+HSC X LC) OR ± ZC Unit 10-3m div 10-3m 10-3m 1 2 3 4 Mean D= r= 22 | P a g e Result (i) The unknown resistance of the given coil of wire (X) = ………………..ohms. (ii) The Specific resistance of the given coil of wire (ρ) = …………ohm-m. 23 | P a g e