Physics Lecture Demonstrations
Demonstrations suggested for the text
Physics for Scientists and Engineers, 2nd ed., by
Randall D. Knight
Revised Tue Jan 24 08:22:01 2012
Please note that first semester related listings may reflect the first edition of the book
Chapter1--Concepts of Motion
||Magnetic Blackboard Vectors
||A set of magnet-backed vectors of lengths 3, 4, and 5 used to show vector addition on the blackboard.
||Linear Air Track: Position vs. Time
||A glider travels down the 5 m air track while evenly spaced photogates record the elapsed time. One can then plot the position versus time for the glider on an overhead. The track may be inclined for uniformly accelerated motion.
||Linear Air Track: Instantaneous Velocity
||An air track glider passes through two pairs of closely spaced photogates with each pair separated by 2 meters, enabling instantaneous velocities, accelerations, and predicted distances to be calculated.
||Inclined Air Track
||Prop up one end on an air track and use photogates to time the glider's voyage.
||Crossing the River
||A battery powered tank runs at constant speed on a sheet of paper that is pulled in a direction perpendicular to the tank's velocity.
||A replica of the platinum-iridium bar in Paris that was the international standard for length before 1960.
||One Nanosecond Bar
||A piece of plastic cut to a 1 ns length and imprinted "one nanosecond." Ruler shown for comparison.
||Movie--Powers of Ten
||"Powers of Ten" is a 9 minute film spanning scales from the edge of the universe to the sub-atomic
Chapter2--Kinematics in One Dimension
||Motion Detector and Board
||An ultrasonic motion detector generates a real-time graph of displacement (and/or veloctiy and/or acceleration) versus time as a boards is moved in front of the detector.
||Dime and Feather Tube
||A penny and a feather fall freely inside a glass cylinder that can be evacuated.
||Timed Free Fall -- Lecture Hall
||A metal ball is dropped from 1m and then from 4m into a catch bucket; a precise digital timer records the time of flight for each fall. [May conflict with Shoot-the-Monkey or Timed Free Fall.]
Chapter3--Vectors and Coordinate Systems
Chapter4--Kinematics in Two Dimensions
||Bend the Wall
||Push on a concrete wall and the wall's deflection is detected by the deflection of a laser beam
||Bend the Table
||Stand on the demo table and show the tabletop deflection by the dispalcement of a laser beam.
||Second Law--Fan Propelled Cart
||Launch a fan-propelled (constant acceleration) cart down the track and observe what happens when its mass is varied.
||Block on a Cart
||A block is placed on a rolling cart; when the cart is stopped, the block continues.
||Dynamics Cart with Force and Motion Sensors
||Use a motion sensor with a force sensor mounted on a dynamics cart pulled by a constant tension string to illustrate Newton's second law. The mass of the cart and the string tension can be varied.
Chapter5--Force and Motion
||Suspended 3-4-5 Block
||A 1 kg mass rests on a 3-4-5 incline (e.g. incline angle = arctan(3/4)). Forces parallel and perpendicular to the incline will support the mass in mid-air when the incline is removed.
||Tension in a String
||The weight of a mass hung from a spring scale is compared to the weight shown on a spring scale between two masses over pulleys
||A mass is hung at the end of a series of spring scales with an intervening mass.
||Rope and three students
||Two large strong students pull on the ends of a rope and a small student pushes down in the middle.
||Friction Cars on Inclined Plane
||The static or dynamic forces required to move teflon-coated, rubber-coated, and wooden carts on an inclined plan are displayed on a spring scale
||Coffee Filter Drop
||One coffee filter dropped from one meter and four coffee filters dropped from 2 meters hit the ground at the same time, demonstrating that the drag force is proportional to the square of the velocity
Chapter6--Dynamics I -- Motion Along a Line
||Shoot the Monkey
||An air-gun shoots at a monkey, released when the air-gun is fired; the bullet hits the monkey in mid-air. [May conflict with Timed Free Fall or Balls Shot and Dropped.]
||Range of a Gun
||Shoot at 45, then calculate 30 or 60 and place the target
||Jumping Ball on Cart
||A ball projected vertically upward from a wheeled cart falls back into the muzzle.
||Balls Shot and Dropped -- Lecture Hall
||A ball is dropped and simultaneously another is projected horizontally; they hit the floor at the same time. [May conflict with Shoot-the-Monkey and Timed Free Fall.]
||Blocks Nudged and Hit
||A meter stick, fixed at one end, is bent and released to simultaneously knock blocks off the table.
Chapter7--Newton's Third Law
||Balls on Rotating Disk
||A disc with two balls mounted at different radii rotates at varying speeds. A third ball may be placed in the center if disk is horizontally mounted. Both orbital and spin rotations may be seen.
||This consists of a large and a small ball attached to opposite ends of a string which passes through a metal handle. The light ball is twirled and the centripetal force is provided by the weight of the heavy ball.
||Satellite Launch Applet
||Animation launching a satellite tangentially to earth surface, as function of velocity: http://www.phy.ntnu.edu.tw/ntnujava/msg.php?id=47
||Ball Orbiting inside Cone
||A large glass cone is used to show circular and elliptical orbits, conservation of angular momentum, and the speed-height paradox.
||Loop the Loop
||A rolling ball must be released from a height equal to 2.7 times the radius of the loop.
||Swing the Bucket
||Swing a bucket of water in a vertical circle and then in a horizontal circle over your head.
||This demo uses an apparatus that rotates a ball on a string and that provides a means to cut the string while the ball is in flight.
Chapter8--Dymanics II -- Motion in a Plane
||Tennis Ball Cannon
||A cannon mounted on an air track glider shoots out a tennis ball horizontallly.
||3rd Law with Scales
||Pull on two coupled spring scales with springs of equal or unequal strength.
||3rd Law with Bathroom Scales
||Have two students push against bathroom scales laid back-to-back to verify that each scale reads the same.
||Fan Cart with Sail
||A cart with a sail propelled by a battery powered fan shows interesting third law behavior.
||Double Pulley Setup
||A 500g mass balances a 1000g mass in a two pulley system; can show that the work done by each in moving is the same.
||Bosun's Chair -- Single Pulley
||Subject in harness with attached rope that flows through overhead pulley, pulls self up with a force equal to half subject's weight.
||Weights of a proportion of 5-to-1 are the equilibrium conditions for this compound pulley.
||Two equal masses are hung from a pulley. A small amount of mass is transferred from one side to the other.
Chapter9--Impulse and Momentum
||Measuring Impulse with Force Sensor
||A force sensor mounted on a cart collides with a barrier, and different force vs. time curves are obtained when the cart bumper is changed.
||Egg in sheet
||Throw an egg into a sheet held by two people.
||Spring apart Pasco carts
||Tripping the spring between two Pasco carts launches them in opposite directions; the cart masses may be varied.
||A toy rocket is launched twice, once when pumped up with air and once when pumped up with water.
||Bowling Ball Pendulum
||A bowling ball pendulum is pulled back until it touches the lecturer's nose and let go. The lecturer does not move.
||Galileo's Pendulum and Nail
||A pendulum started at the height of a reference line reaches the same height when its swing is intercepted by a post that effectively shortens the length of the pendulum.
||Toys - Jumping
||A spring-loaded object (jumping disk; jumping frog) can often jump many times its own height.
||Spring-Launched Rolling Cart
||Predict the height to which a spring-compressed cart will rise on an inclined plane given the mass, spring constant, and amount of spring compression. Do the experiment.
||Five adjacent metal balls on a bifilar suspension illustrate momentum conservation properties.
||Compare a steel ball bouncing on an amorphous metal to one bouncing on stainless steel.
||Happy and Unhappy Balls
||Two black rubber balls of about 1.5 cm diameter are dropped from a height simultaneously. One ball bounces high while the other barely rebounds. Great to pass around.
||Movie: Honda Cog
||Two-minute Honda movie ad of a series of mechanical cogs bumping into each other in sequence. http://www.youtube.com/watch?v=EEF0cg1j35
||Drive a nail into a block of wood with a pile driver.
||Spring Launched Cart on Level Track
||A spring (of measurable spring constant) launches a cart (with measurable final veloctiy) on a level air track. Mass of cart can be varied.
Chapter12--Rotation of a Rigid Body
Chapter13--Newton's Theory of Gravity
||Throwing Foam Slab
||A slab of foam has its center of mass marked with a black dot; this dot follows a parabolic path when the slab is thrown.
||A long thin rid mounted perpendicular to a bar handle holds a 2 kg mass on a sliding collar.
||Movie: Milwaukee Pitstop Ad
||A humorous, fake video showing a car being rotating by a torque wrench. http://www.youtube.com/watch?v=q5LrarVz94g
||Equal Arm Balance
||Combinations of weights and distances on either side of the fulcrum of the equal arm balance may be selected to produce equilibrium. An oblique arm is used to show that the effective length of the lever arm is set by the component of the force.
||Students twirl equal mass wands, one with the mass concentrated in the middle, the other with the mass concentrated at the ends.
||Two equal masses with adjustable positions are mounted on a radial bar fixed to a horizontal axis with a pulley. A weight on a string rotates the assembly.
||Suspend a 2-dimensional shape from holes drilled near the edges, and use a plumb bob to find the center of gravity.
||Meter Stick on Fingers
||Slide fingers together under a meter stick to come together at center of mass. Repeat with mass attached to one end of stick.
||Ladder against a Wall
||Set a ladder against the wall and walk up the rungs until the ladder begins to slide.
||Walking the Spool
||The spool can roll forward or backwards when the string is pulled, depending on the angle of pull.
||Photo: Pisa's Leaning Tower
||Digital image of the photo from Bloomberg's sixth floor of the Leaning Tower of Pisa. May be projected in the auditorium.
||Center of Gravity Blocks
||Stack blocks stairstep fashion at the edge of the table until the topmost block sticks out beyond the table edge.
||Tight Rope Walker
||The Tight Rope Walker consists of a pulley with four heavy lead weights on long semi-stiff wires symmetrically mounted around it. When placed on the "rope" (Cord), the weights hang down well under the rope, leaving the center of the Walker's mass below the rope and thus making it easy for the Walker to keep its balance.
||Ring versus Disk Race
||The Matched Disk and Ring are identical in diameter and mass. When rolled down the inclined plane, the disk wins the race due to its lower moment of inertia.
||Two disks of identical mass, one weighted in the center and the othe weighted at the rum, are rolled down an incline.
||Collapse a spinning suspended Hoberman Sphere into a small ball.
||This motorized gyroscope, used in the teaching labs, is good for showing a gyroscope's directional constancy; precession due to applied torques, and nutation.
||A steel cylinder is suspended by a steel music wire along its right axis. When the cylinder is displaced by rotation and released it will oscillate in simple harmonic motion.
||Spring and Air Cart
||An air track glider is attached to a horizontal spring and displaced from equilibrium.
||Air track glider and Spring
||Two identical air track carts are attached to (opposite) ends of an air track by means of two different springs. A mass may be added to either cart, and the dependence of the oscillation frequency on mass and on spring constant may be explored.
||Shadow project a ball mounted on a rotating disk.
||Spring and Weight
||A mass hangs on the end of a spring. Using two springs of different k and a variety of masses, show the effect of varying k and m.
||Springs in Series and Parallel
||A spring with mass m, two identical springs in parallel with mass 2m, and two identical springs in series with mass m/2 oscillate with the same period.
||A bob on a string hanging from a stand exhibits simple harmonic motion for small angles.
||One pendulum four times longer than a second oscillates with twice the period of the second.
||Different mass pendula
||Three pendula of different masses but the same length all oscillate with the same period.
||Pendula Amplitude Dependence
||Two identical simple pendula set in motion with different initial amplitudes, oscillate nonisochronically.
||Tacoma Narrows Film
||A 3 minute video of the collapse of the Tacoma Narrows Bridge. Very impressive and memorable.
||Damped Driven Hanging Mass
||A mass, supported by a spring whose support is driven, vibrates against a solid screen; the drive amplitude, frequency and the screen angle can be varied.
Chapter15--Fluids and Elasticity
||Tubes of different geometries rise vertically out of a common reservoir of colored water.
||Water streams out from three holes at different heights in a tall cylinder.
||Weigh Submerged Block
||A 2 kg Al cylinder, suspended from the 20 N spring scale, is lowered into water and the new weight is observed; Can have beaker on scale; Can lower into oil for comparison
||Finger in Water
||Ask what will happen when a finger is inserted into a beaker of water balanced on a pan balance.
||Coke and Diet Coke
|| An unopened diet soda can floats in water, and a regular soda can sinks.
||Air flows through a restricted glass tube to the atmosphere; the pressure at different points of the tube is shown by manometers.
||Funnel and Ball
||A ping-pong ball is supported by air streaming out of an upside down funnel.
||Fan blowing on Board
||A fan blows on a board mounted so that it can rotate about an axis in the wind. What orientation will the board take?
||Hold one of these cards horizontally in the air, and then drop one to observe the dominate behavior of the card orienting itself horizontally, as well as the slipping and rotating behavior believed due to turbulence.
||Blow up an 8-foot long bag with one breath.
||Ping Pong Ball and Racket
||Use a ping pong racket to hit a curve ball using a 2-3" diameter styrofoam ball or a ping pong ball.
||Swimming in Corn Syrup Movies
||Three movies showing a flap-drive in water, flap-drive in corn syrup, and corkscrew-drive in corn syrup, from Youtube.
||Hand weights from a wire, and use a laser and mirror-mounted-on-lever to display the elongation.
Chapter16--A Macroscopic Description of Matter
Chapter17--Work, Heat, and the First Law of Thermodynamics
Chapter18--The Micro/Macro Connection
Chapter19--Heat Engines and Refrigerators
||Pulse on 1.9m spring
||Give the 1.9 m spring a quick pulse. The length and/or tension in the spring can be varied. Good for showing pulses, standing waves, harmonics, energy transfer.
||Pulses on Torsional Wave Apparatus
||Excite the short-bar and long-bar torsional wave machines by hand to show how the wave speed varies as the inertia of the medium (the rod length) varies.
||A long slinky is supported on a bifilar suspension, and the ends are taped to the lab stands, for showing longitutinal wave properties with minimal friction. [BROKEN]
||Driven Rope Waves
||A horizontal rope with a mechanical vibrator at one end and a weight over a pulley at the other end is used to show standing waves at different driving frequencies. [Needs Fixing]
||Standing Waves on a String
||Use a mechanical vibrator to generate standing waves on a string with one end under tension from a hanging mass. Best under UV light
||Speed of Sound by Phase Difference
||A function generator drives a speaker, and an oscilloscope displays the signals from the function generator and a microphone that moves radially from the speaker.
||Speaker and Candle
||A large speaker operating at low frequncy and large amplitude makes a candle flame oscillate.
||Rub the edge of a goblet with a wet finger to make it sing. An oscilloscope can be used to measure the frequencies.
||Swing a small battery powered buzzer on the end of a string in a circle over your head.
||HeNe Laser exposed
||Examine an exposed operating HeNe laser cavity with a diffraction grating.
||Hanging weights on the end of a "guitar" can be varied to "tune" the guitar to a desired pitch.
||A long tube is rolled in front of a speaker driven by a sine wave generator to show resonance. A microphone probe shows pressure variations on the o-scope.
||Show nodes and antinodes with the flames coming from a row of holes in a hollow tube filled with propane.
||A closed-end, square wood organ pipe of adjustable length.
||A student-class trombone illustrates the effect of pipe length on resonant frequencies.
||A driven Chladni plate covered with sand shows standing wave patterns. Noisy!
||A 2 meter long bar with a speaker at each end produces auditory interference patterns.
||Two Speakers and Microphone
||Use a microphone attached to an oscilloscope to display the interference patterns produced by two identically-driven speakers
||Two Points in Ripple Tank
||Two point source generators of ripples show interference patterns in the ripple tank on the overhead projector.
||Moire Pattern Transparancies
||Transparancies with identical concentric circular patterns are placed on top of each other with a slight offset.
||Beats with Tuning Forks
||Two tuning forks of identical frequency are mounted on resonant enclosures; when a small piece of wax is attached to one, beats can be heard.
||Beats on Scope
||Two audio signals are fed through a summing amplifier and the result is presented on the oscilloscope and a speaker.
||Double Slit and Laser - Cornell Slitfilm
||Use a laser bean on the slits on the far column of the Cornell slitfilm to show the effect of increasing the spacing between a pair of slits, with the slit spacing held constant. The first entry is a single slit.
||Types of Diffraction Gratings
||Transmission and Reflection, Blazed and Not, Diffraction Gratings of different line densities probed by a laser.
||Single Slit in Ripple Tank
||Diffraction from a plane wave passing through a single slit on the ripple tank mounted on the overhead projector.
||Pin hole diffraction - projected
||View the diffraction pattern of a pinhole; a variety of pinhole dimensions are available. The photo shows 100 um and 50 um round pinhole patterns and 100 um and 50 um square patterns.
||Stick in Water
||A stick appears bent when inserted into the water at an angle.
||Show (with a laser pointer) and tell with optical fibers
||A beam of light shines through a tank of slightly milky water onto the wall.
||Two concave mirrors face each other. The top mirror has a hole allowing light to enter and escape. An image of the objects resting on the bottom of one appears at the center hole of the top mirror.
||Working Eye Model
||A model demonstrates the focal capabilities of the normal, nearsighted, and farsighted eye.
Chapter25--Modern Optics and Matter Waves
||Electrons passing through a carbon target produce a circular diffraction pattern.
Chapter26--Electric Charges and Forces
||Charged Rods on Pivots
||A charged rod on a pivot is used to show attraction and repulsion by another charged rod.
||Conductors and Insulators
||Shows that charge can be transferred to an electroscope through conductors but not insulators
Chapter27--The Electric Field
||Hair on End
||Charge yourself with a Van de Graaff generator
||Show that an electron beam passing between charged, parallel plates is deflected using an oscilloscope (view along beam)
||Show that charge resides on the outside of a hollow conductor.
||Gauss with Electric Field Visualizer
||Tiny fibers in a clear oil that align in the direction of strong applied electric fields remain randomly oriented inside a charged ring.
||Radio in a Cage
||Surround a radio by a Faraday cage and the signal goes away
Chapter29--The Electric Potential
Chapter30--Potential and Field
||Van de Graaff Generator
||Describe the operation of the Van de Graaff and show sparks from the ball to a nearby grounded conductor.
||Stick copper and zinc electrodes into a lemon and measure the potential difference with a voltmeter
||Use a proof plane and an electroscope to compare charge densities at different points on an egg-shaped conductor.
||Electrical arcing between two large metal spheres abruptly ceases when the lightning rod is touched to one.
Chapter31--Current and Resistance
||Place 6V across a set of wires of different diameters and measure the currents.
||Conduction in Glass
||Heat a glass rod with a flame until its resistance is low enough to sustain conduction.
||An arc rises between rabbit ear electrodes attached to a high voltage source.
Chapter32--Fundamentals of Circuits
Chapter33--The Magnetic Field
||Show that the lodestone attracts small nails and paperclips.
||Magnets on Pivots
||One magnet is placed on a pivot. The other is used to attract or repel the first
||B-Field due to single coil.
||Iron filings are sprinkled on a plexiglas plate through which a single loop of current-carrying wire is mounted
||B-Field due to solenoid
||Iron filings are sprinkled on a plexiglas plate through which a current-carrying solenoid is mounted.
||Deflect the beam in an e/m tube with magnets
||A magnet exerts a torque on a current-carrying coil.
||World's Simplest Motor
||A simple DC motor that requires only a battery, a bare wire, a nail, and a magnet.
||The Barkhausen Effect
||Clicking noises are heard when a magnet is brought near iron wire within a pickup coil.
||Audible Pickup Coil
||Generates sounds in a pickup coil connected to a speaker with a steel tuning fork.
||Eddy Current Pendulum
||A copper sheet, a comb, a ring, and a broken ring are swung through a large electromagnet.
||A solid conducting ring sitting on a vertical solenoid jumps and a split ring doesn't
||Generate a DC current by rotating a loop with a split-ring connection in a magnetic field.
||This flashlight runs on induction-induced currents, a capacitor, and an LED lightbulb.
||Demonstrate step-up and step-down transformers.
||Rotating a wire loop in a magnetic field generates an AC current in the loop.
||A bright spark is produced when the switch of a large electromagnet is opened
Chapter35--Electromagnetic Fields and Waves
||Insert a beaker of liquid sugar between crossed polaroids.
||AC and DC Lamps
||A magnet is brought near two carbon filament bulbs, one DC powered and one AC powered.
||RC Circuit -- Phase relations
||Show the potential difference across the power supply, the resistor, and the capacitor as a function of frequency, resistance, or capacitance.
||RL Circuit -- Phase relations
||Show the potential difference across the power supply, the resistor, and the inductor as a function of frequency, resistance, or inductance.
||60 Hz LRC circuit
||Shows the potential difference across the Capacitor and Inductor at resonance.
Chapter38--The End of Classical Physics
||Project the spectrum of an incandescent bulb as a function of temperature.
||Vibrating Circular Wire
||A circular wire driven by a function generator produces standing waves at resonant frequencies.
Chapter40--Wave Functions and Uncertainty
Chapter41--One-Dimensional Quantum Mechanics
||Quantum Dots - InP solution
||Four vials of InP quantum dots of different diameter fluoresce with different colors under violet light
||Diffusion Cloud Chamber
||A diffusion cloud chamber shows the tracks from cosmic rays and from alpha, beta, gamma, and X-ray sources.
Physics Lecture Demonstrations at
the Department of Physics and Astronomy
The Johns Hopkins University