Scholarship Physics 93103

Mechanics, electricity, waves and modern physics. Unfamiliar contexts, show-that derivations and extended explanations, modelled on NZQA papers 2004–2025.

450 problems · 20 free to try now

Full Physics bank coming soon

All 450 problems with hints, worked solutions and mark guides. Leave your email and we’ll tell you the day full access opens.

TierAll Bridge Scholarship

Mechanics · 158

The Runaway Cable DrumRotational dynamicsBridge
Skid to Roll at the Bowling AlleyRotational dynamicsScholarship
Despinning the CubeSat CarrierRotational dynamicsScholarship
Raising the PouRotational dynamicsScholarship
Mahia to Low Earth OrbitCircular motion and gravitationBridge
Loop-the-Loop in an Electric FieldCircular motion and gravitationScholarship
Weighing Stars from TakapōCircular motion and gravitationScholarship
The Rubble-Pile Spin LimitCircular motion and gravitationScholarship
Conversion in Front of the PostsProjectiles and forcesBridge
Uphill Kick on Mt VictoriaProjectiles and forcesScholarship
The Bouncing CoinSHM and oscillationsBridge
The Base-Isolated ModelSHM and oscillationsScholarship
The Swinging SculptureSHM and oscillationsScholarship
The Head-On TackleMomentum and collisionsBridge
Glancing Stones at NasebyMomentum and collisionsScholarship
Gravel on the BeltMomentum and impulse (variable mass)Scholarship
Freefall over TaupōForces, drag and terminal velocityScholarship
Timing the FlywheelRotational dynamicsBridge
The Wardrobe on the UteRotational dynamics (toppling versus sliding)Scholarship
The Swinging Archery TargetRotational dynamics (angular momentum in collisions)Scholarship
Which Way Will the Spool Roll?Rotational dynamics (rolling with friction)Scholarship
Banking at the VelodromeCircular motion (banked track)Bridge
Cheaper to Leave than to Climb?Gravitation and orbits (orbit transfer, escape)Scholarship
Falling on a LeashGravitation and orbits (orbital decay, with electromagnetic induction)Scholarship
Gravity by SpinCircular motion (rotating frames, artificial gravity)Scholarship
Hauling the Waka AmaForces and frictionBridge
The Ice Cube and the Rolling RampForces and momentum (block on a free wedge)Scholarship
Speed Bumps and a Loaded UteSHM and oscillations (resonance)Bridge
The Bobbing Channel MarkerSHM and oscillations (buoyancy)Scholarship
Slosh in the U-TubeSHM and oscillations (liquid column, damping, LC analogue)Scholarship
Jumping off the DinghyMomentum and collisions (recoil)Bridge
Lift-off from MāhiaMomentum and impulse (variable mass, rocket thrust)Scholarship
Splitting Shells over the HarbourMomentum (explosions, centre of mass)Scholarship
Braking Down Baldwin StreetForces (friction on a slope)Scholarship
The Kick-Wheel in the Pottery StudioRotational dynamics (rotational kinetic energy)Bridge
Two and a Half Tuck from the TenRotational dynamics (angular momentum about the centre of mass)Scholarship
The Ladder on the Woolshed WallStatics (friction at two surfaces)Scholarship
Ball Bearing in the BowlRotational dynamics (rolling on a curved surface)Scholarship
Over the HumpCircular motion (vertical circle)Bridge
Too Close to SaturnGravitation (tidal forces)Scholarship
Halfway to the Moon?Gravitation (field and potential energy)Scholarship
The Chair-Swing at the A&P ShowCircular motion (conical pendulum)Scholarship
Drop ZoneProjectiles (horizontal launch)Bridge
Designing the Arc FountainProjectiles (fluid jets)Scholarship
The Clock at the Top of the GondolaSHM and oscillations (pendulum, variation of g)Bridge
The Snapper on the Spring BalanceSHM and oscillations (vertical spring, energy bookkeeping)Scholarship
The Pendulum in the Cable CarSHM and oscillations (pendulum in an accelerating frame)Scholarship
The Watch That Loses Time OvernightSHM and oscillations (oscillator frequency drift with temperature)Scholarship
Straight Back Past the BowlerMomentum and impulse (force–time pulse)Bridge
Counting the ClicksMomentum and impulse (repeated bounces, geometric series)Scholarship
Jet Ski on Lake TaupōMomentum (mass flow, jet propulsion and efficiency)Scholarship
Out and Back into the NortherlyForces (drag, rolling resistance and power)Scholarship
Squeezing the Disc BrakeRotational dynamics (braking torque, work and energy)Bridge
The Falling ChimneyRotational dynamics (falling rod, hinge forces)Scholarship
Rolling Off the DomeRotational dynamics (rolling, loss of contact, onset of slipping)Scholarship
Walking Out on the RoundaboutRotational dynamics (angular momentum transfer, friction limit)Scholarship
Inside the Spin CycleCircular motion (vertical circle, rotating drum)Bridge
A Satellite for Scott BaseGravitation and orbits (elliptical orbits, Kepler's laws)Scholarship
Twisting Fibre, Tiny ForceGravitation (torsion-balance measurement of G)Scholarship
Borrowing Speed from JupiterGravitation (gravity assist, conservation laws)Scholarship
The Coin in the Tower LiftForces (Newton's second law in an accelerating lift, relative motion)Bridge
Pulling the Sled from Under the Chilly BinForces (friction between stacked bodies)Scholarship
Bouncing on the TrampolineSHM and oscillations (spring model, energy, contact time)Bridge
The Ball in the Bottle NeckSHM and oscillations (gas spring, isothermal vs adiabatic)Scholarship
The Hoop on the PegSHM and oscillations (physical pendulum, parallel-axis theorem)Scholarship
Clocking the CatapultMomentum and collisions (ballistic pendulum)Bridge
Two In, Two OutMomentum and collisions (elastic collisions, Newton's cradle)Scholarship
The Pumpkin Cannon on the RampMomentum and impulse (recoil on an incline, component conservation)Scholarship
The Baggage TrainForces (connected bodies, tension and compression, friction limit)Scholarship
The Maxwell WheelRotational dynamics (string-wound wheel, tension and energy)Bridge
Which Way Does the Road Push?Rotational dynamics (rolling wheels, friction direction, effective mass)Scholarship
Letting Go of the BeamRotational dynamics (statics and sudden release, support forces)Scholarship
The Rod on the TrolleyRotational dynamics (rolling on an accelerating surface)Scholarship
The Lengthening DayRotational dynamics (angular momentum transfer, tidal braking)Scholarship
Teardrop LoopsCircular motion (vertical loops, variable radius of curvature)Bridge
Keeping GPS on ScheduleGravitation and orbits (orbital radius, signal timing, station-keeping)Scholarship
Riding the Space ElevatorCircular motion and gravitation (rotating cable, release and escape)Scholarship
Catch on the EscalatorProjectiles (relative motion, inertial frames)Bridge
Finding the Arc for a Free ThrowProjectiles (trajectory to a raised target, entry angle)Scholarship
The Pendulum WaveSHM and oscillations (simple pendulum, phase)Bridge
The Puck on the Elastic CordSHM and oscillations (transverse and longitudinal, elastic cord)Scholarship
The Bead Between Two ChargesSHM and oscillations (electrostatic restoring force, stability)Scholarship
Springs Between AtomsSHM and oscillations (atomic vibrations, Young's modulus)Scholarship
Board Swap at the Skate ParkMomentum and collisions (recoil and perfectly inelastic landing)Bridge
Holding Up a HelicopterMomentum and impulse (momentum flux, hovering power)Scholarship
The Basketball CannonMomentum and collisions (elastic collisions, stacked balls)Scholarship
The Rising Weather BalloonForces (buoyancy, drag and terminal speed)Scholarship
The Pole on the High WireRotational dynamics (torque, rotational inertia, toppling)Bridge
Spin and Slide on the IceRotational dynamics (friction torque, coupled sliding and spinning)Scholarship
Dominoes That GrowRotational dynamics (toppling, rotational kinetic energy)Scholarship
Landing on Its FeetRotational dynamics (zero angular momentum, reorientation by shape change)Scholarship
Speed Table on the RoundaboutCircular motion (friction on a flat curve, vertical curvature)Bridge
Twenty Seconds of FloatingCircular motion and free fall (parabolic flight, apparent weight)Scholarship
Whose Moon Is It?Gravitation (tidal acceleration, Hill radius)Scholarship
Riding the Wall of DeathCircular motion (friction on a vertical wall, torque balance, lean angle)Scholarship
Winching onto the Tilt TrayForces (inclined plane, pulley systems, work and power)Bridge
Catching the BoosterForces (drag, terminal speed, parachute opening load)Scholarship
The Pendulum Above the Top FloorSHM and oscillations (simple pendulum, tuned mass damper, resonance)Bridge
Weighing Without WeightSHM and oscillations (inertial mass from period, calibration, free fall)Scholarship
Setting the TempoSHM and oscillations (compound pendulum, torque, stability)Scholarship
Letting Go of the SandbagMomentum and collisions (release versus throw, relative velocity)Bridge
Driving the Fence PostMomentum and collisions (perfectly inelastic impact, work–energy)Bridge
Reading the Skid MarksMomentum and collisions (two-dimensional inelastic collision, friction, reconstruction)Scholarship
Nudging the PlanetMomentum (linear and angular momentum in an impact, estimation)Scholarship
Pushing the Revolving DoorRotational dynamics (torque, rotational inertia, work done by a torque)Bridge
The Sagging Farm GateTorque and statics (hinge forces), angular momentum about a fixed axisBridge
Load Rejection at the Power StationRotational dynamics (torque balance, rotational kinetic energy) with circular motion (centripetal force on rotor poles)Scholarship
The Disc That Spins ItselfRotational dynamics (angular impulse) with electromagnetic inductionScholarship
Smoke at TouchdownRotational dynamics (friction torque, sliding to rolling, energy dissipation)Scholarship
The Plumb Line in WellingtonCircular motion (Earth's rotation, apparent weight, direction of the vertical)Bridge
Nudging a MoonletGravitation and orbits (orbit change from an impact) with momentum conservationScholarship
Separating the CreamCircular motion with buoyancy and viscous drag (centrifugal separation)Scholarship
The Best Angle for the Shot PutProjectiles (optimum launch angle from a height, velocity vector triangle)Scholarship
Splitting the FirewoodStatics with friction (wedge, mechanical advantage, self-locking)Scholarship
The Phone on a StringSHM and oscillations (simple pendulum, graph linearisation, systematic error)Bridge
The Proof Mass in Your PhoneSHM and oscillations (MEMS accelerometer, spring–mass, differential capacitor)Scholarship
Swinging the BotafumeiroSHM and oscillations (parametric pumping of a pendulum, angular momentum about a pivot, energy)Scholarship
The Swinging SpringSHM and oscillations (elastic pendulum, 2:1 resonance, energy exchange)Scholarship
Surging at Lake KarapiroMomentum and collisions (internal forces, centre-of-mass velocity, rowing)Bridge
Filling the Feed BagsMomentum and collisions (momentum flux of a falling stream, inelastic landing, weighing while filling)Scholarship
Squeezing the PuckMomentum and collisions (elastic rebound from a moving barrier, adiabatic invariant)Scholarship
Leaning into a Wellington GustStatics (torques about a pivot, friction limit, wind drag)Bridge
Striking for a Natural RollRotational dynamics (angular impulse, rolling without slipping, direction of friction)Bridge
Holding the Iron CrossTorque and statics (rotational equilibrium of a limb, muscle and joint forces)Bridge
Timing a Bat to Find Its Sweet SpotRotational dynamics (centre of percussion, angular impulse, effective mass) with the physical pendulumScholarship
Planting a Rigid PoleRotational dynamics (angular momentum about a pivot, impulsive forces, energy loss) in pole vaultingScholarship
The Turbo Trainer That Feels WrongRotational dynamics (coupled rotating bodies, effective mass) with EM induction (eddy-current brake)Scholarship
Over the Top on a Kiiking SwingCircular motion (vertical circle, rigid support versus rope, apparent weight)Bridge
Games on DeimosGravitation (surface field, escape and orbital speeds, non-uniform field) with circular motionScholarship
Spiral Dive over the LakeCircular motion (steady helical turn, load factor, aerodynamic force)Scholarship
Clocking the ServeForces (quadratic drag on a projectile) with the Doppler effect for microwavesScholarship
Rigging the SlacklineStatics (tension in a sagging line, elastic stretch, small-angle geometry)Scholarship
Bounce at the Ground FloorSHM and oscillations (elastic rope as a spring, sudden loading)Bridge
Why Railway Wheels Are ConesSHM and oscillations (kinematic oscillation of a coned wheelset) with circular-motion kinematicsScholarship
Stiff Ship, Tender ShipSHM and oscillations (rolling ship, righting couple, angular SHM) with torque and rotational dynamicsScholarship
The Snatch StrapMomentum and collisions (elastic link between two vehicles, energy storage, impulse)Bridge
Berthing the FerryMomentum and collisions (eccentric impact, linear and angular impulse, fender energy)Scholarship
Sand Barrels at the Off-RampMomentum and collisions (sequential inelastic collisions, crash-cushion design)Scholarship
The Gap Behind the HeadboardMomentum and impulse (relative motion, internal impact, friction, load restraint)Scholarship
Fifty or Sixty?Forces and kinematics (friction braking, reaction distance, stopping distance)Bridge
Slewing the Tower CraneRotational dynamics (rotational inertia, torque, angular momentum) with circular motion of a hanging loadBridge
Riding Through the BlackoutRotational dynamics (rotational kinetic energy, flywheel storage) with DC circuits (emf, internal resistance, power)Scholarship
Parking the Wind TurbineRotational dynamics (gearbox torque, braking, energy dissipation) with circular motion (blade root forces)Scholarship
Friction on the Winding WheelRotational dynamics (torque on a friction-driven winding wheel, rope friction limit)Scholarship
Fifty g in the Soil LabCircular motion (centripetal acceleration, swinging basket, scale modelling)Bridge
Weighing the Hidden Ore BodyGravitation (field of a buried sphere, gravity anomaly, vertical component)Bridge
The Weighted GovernorCircular motion (linked masses in horizontal circles, centrifugal governor)Scholarship
Heavier at the Bottom of the ShaftGravitation (field inside the Earth, shell theorem, mean density)Scholarship
Slinging the Bridge BeamStatics (sling tensions, resolving forces, torques about the centre of mass)Bridge
Sorting Sand in Free FallForces and two-dimensional motion in uniform fields (gravity and an electric field), with air resistanceScholarship
Crossing the Kāwhia BarSHM and oscillations (SHM model of the tide, reference circle, rates of change)Bridge
The Dolphin Listener's MooringSHM and oscillations (buoyant inverted pendulum, added mass, drag in a current)Scholarship
Wingbeats on the RadarSHM and oscillations (angular SHM of a flapping wing) with radar Doppler shift (inclined beam, line-of-sight components, inverse measurement)Scholarship
Bruised Apples in the BinMomentum and impulse (impulse–momentum theorem, average force, effect of rebound)Bridge
The Gannet's PlungeMomentum and collisions (perfectly inelastic impact with water set in motion, impulse, average force, scaling)Scholarship
The Kārearea's StrikeMomentum and collisions (two-dimensional perfectly inelastic collision, work done by internal forces, validity of momentum conservation)Scholarship
Bouncing the BlueberriesMomentum and collisions (oblique impact, coefficient of restitution, impulse) with projectile motionScholarship
Kite Fishing at Ninety Mile BeachForces and statics (equilibrium of a kite, lift and drag scaling, limiting cases)Scholarship

Electricity · 126

Dimming at the IgnitionDC circuits (internal resistance)Bridge
Old Cell, New CellDC circuits (Kirchhoff, cells in parallel)Scholarship
The Boat-Ramp WinchDC circuits (maximum power transfer)Scholarship
The Open-Evening CapacitorCapacitors, dielectrics, RC, energyBridge
The Kiwi Camera Trap TimerCapacitors, dielectrics, RC, energyBridge
The Missing JoulesCapacitors, dielectrics, RC, energyScholarship
The Electrostatic GripperCapacitors, dielectrics, RC, energyScholarship
The Rooftop Wind GeneratorEM induction, Faraday/Lenz, LRBridge
The Regenerative Rail BrakeEM induction, Faraday/Lenz, LRScholarship
The Gate-Latch ElectromagnetEM induction, Faraday/Lenz, LRScholarship
Stopping the ZiplineEM induction, Faraday/Lenz, LRScholarship
Tuning the Series CircuitAC: reactance, phasors, LCR, resonanceBridge
The Wireless Charging PadAC: reactance, phasors, LCR, resonanceScholarship
Tuning In on the Kāpiti CoastAC: reactance, phasors, LCR, resonanceScholarship
Lights in the Far ShedDC circuits (cable resistance)Bridge
The Weigh-Link on the Wharf CraneDC circuits (Wheatstone bridge, strain gauge)Scholarship
Designing the Foam CutterDC circuits (heater design, temperature coefficient)Scholarship
The Supercapacitor Bike LightCapacitors, RC discharge, energyBridge
The Sports-Club DefibrillatorCapacitors, RC discharge, energyScholarship
The Attracted-Disc VoltmeterCapacitors, electrostatic force, energyScholarship
Lighting the Garden PathEM induction, transformers, LenzBridge
Counting Chairs on the LiftEM induction, Faraday/Lenz, flux linkageBridge
The Falling-Weight Disc DynamoEM induction, motional emf, rotational dynamicsScholarship
The Ignition CoilEM induction, mutual inductance, LR, inductor energyScholarship
The Tweeter's CapacitorAC: reactance, phasors, RC filterBridge
Correcting the Pump MotorAC: phasors, power factor, reactanceScholarship
Beeping at the BeachAC: LC resonance, inductance, beatsScholarship
The Constant-Resistance CrossoverAC: reactance, phasors, LCR, resonanceScholarship
The Glasshouse Frost AlarmDC circuits (potential divider, thermistor, loading)Bridge
The Leaky Electric FenceDC circuits (ladder network, self-similarity)Scholarship
The Hut's Solar PanelDC circuits (non-ohmic source, maximum power)Scholarship
Two Capacitors for One JobCapacitors in series, leakage, RC dischargeBridge
The Thundercloud CapacitorCapacitors: parallel-plate field and energyBridge
Listening with a CapacitorCapacitors: constant charge, electrostatic force, RCScholarship
Flipping for the FieldEM induction: flux change and chargeBridge
The Slow Fall Through CopperEM induction: eddy currents, Lenz, terminal speedScholarship
The Rail LauncherEM induction: force on a current, back emf, energyScholarship
Octaves from a PickupEM induction: varying flux linkage, guitar pickupScholarship
The Capacitor Night-LightAC: capacitive reactance, phasors, powerBridge
Dimming the Stage LampAC: power, power factor, rms of non-sinusoidal waveformsScholarship
The Three-Voltmeter CoilAC: phasors, real inductor (three-voltmeter method)Scholarship
The Relay That BuzzesAC: RL circuit, transient vs AC responseScholarship
Choosing the LED ResistorDC circuits (non-ohmic LED, series resistor, load line)Bridge
Fast or Slow Charging?DC circuits (charging against an emf, internal resistance, losses)Scholarship
Sizing the Fuse WireDC circuits (Joule heating, fuse design, scaling)Scholarship
Smoothing the Bench SupplyCapacitors: RC discharge, smoothing rippleBridge
Charging the Bus at the StopCapacitors: energy stored, charging lossesBridge
How High Can the Dome Go?Capacitors: isolated sphere, breakdown field, leakageScholarship
The Bulb That Changes Its MindCapacitors: RC discharge with a non-ohmic load, log-linear graphScholarship
The Self-Limiting Hub DynamoEM induction: AC generator, self-inductance (bicycle hub dynamo)Bridge
Harvesting the Pump's HumEM induction: electromagnetic damping, maximum power transfer (vibration harvester)Scholarship
Through the Magnetic GateEM induction: loop crossing a field region, emf–position graphs, work and energyScholarship
Starting the Sawmill MotorEM induction: back emf, self-inductance (DC motor starter)Scholarship
Losing the TrebleAC: RL series circuit, impedance, power, phaseBridge
Why the Line Runs at 11 kVAC: transformers, rms power, transmission lossesScholarship
Starting the CompressorAC: phasors, parallel branches, phase shift (capacitor-start motor)Scholarship
The Wind Charger at the BachDC circuits (emf, internal resistance, diode, charging)Bridge
Clearing the Rear WindowDC circuits (resistivity, parallel heater design)Scholarship
Balancing Cells on a Slide WireDC circuits (potentiometer, emf and internal resistance)Scholarship
Why the Lamp Knows You Are ThereCapacitors: parallel and series combinations, RC chargingBridge
Doubling Up in a PacemakerCapacitors: series/parallel switching, RC discharge, charging efficiencyBridge
Earth's Leaky CapacitorCapacitors: spherical capacitor approximation, leakage, time constantScholarship
Millivolts on the Main Trunk LineEM induction: motional emf, flux through moving and stationary circuitsBridge
The Magnetic FlowmeterEM induction: motional emf in a conducting fluid (electromagnetic flowmeter)Scholarship
The Geophone's CoilEM induction: moving-coil transducer (geophone), force on a currentScholarship
Loading the Bach Wind TurbineEM induction: generator emf and braking torque, power matchingScholarship
Phantom Volts in the WallAC: capacitive reactance, series RC phasors, source impedanceBridge
Lead and Lag in the WorkshopAC: phasors, parallel RL and RLC branches, power factor, flickerScholarship
Notching Out the HumAC: series LC trap, phasors, notch filterScholarship
The Constant-Current KilnAC: phasors, parallel RC fed through an inductor, constant currentScholarship
Four Wires for a Small ResistanceDC circuits (four-terminal resistance measurement, lead resistance)Bridge
When One Bulb Goes OutDC circuits (series string, shunted failure, non-ohmic filament)Scholarship
How Long Can the Drone Hover?DC circuits (internal resistance, power delivery, energy capacity)Scholarship
Keeping Time in a Power CutCapacitors: constant-current discharge, energy, series cellsBridge
The Wedding Slave FlashCapacitors: RC charging and discharge, energy and p.d., timingBridge
The Ring That Doesn't Make SafeCapacitors: charge redistribution in a loop, reverse charging, RC timingScholarship
Stacking Up a Lightning PulseCapacitors: series/parallel switching (Marx generator), charge sharing, energy lossScholarship
Shake to ShineEM induction: Faraday/Lenz, magnet through a coil, energy and forceBridge
Power Through the SkinEM induction: mutual inductance, wireless power transferScholarship
The Leaping RingEM induction: Lenz's law with AC, phase lag, jumping ringScholarship
Flinging Cans from the RecyclingEM induction: eddy currents, Lenz's law, scaling (eddy-current separator)Scholarship
Iron in the CoilAC: inductive reactance, impedance, core lossesBridge
Listening for the RippleAC: series LCR band-pass, selectivity, Q factor (ripple-control receiver)Scholarship
The Oil-Tank Phase DetectorAC: series LCR off resonance, phase from an oscilloscope (capacitive level sensor)Scholarship
The Kūmara BatteryDC circuits (emf and internal resistance, linearised graph, cells in series)Bridge
Finding the Fault Under Cook StraitDC circuits (Wheatstone bridge, Murray loop fault location)Scholarship
Feet on the Trolley WireDC circuits (resistivity, p.d. along a conductor, current divider)Bridge
Step Voltage at the Earth StakeDC circuits (current spreading in the ground, step voltage, series resistances)Scholarship
Lifting Oil with a VoltageCapacitors: dielectric force from energy, constant p.d., fluid staticsScholarship
The Kelvin Water DropperCapacitors: induced charge, charge accumulation with feedback, energy from gravityScholarship
The Beacon on the RidgeCapacitors: RC charging between thresholds, relaxation oscillator, energy and battery lifeScholarship
Skipping on Earth's FieldEM induction: Faraday/Lenz, rotating loop in Earth's field (field components)Bridge
Dropping the Load at the ScrapyardEM induction: LR circuit growth and decay, inductor energy, discharge resistorBridge
The Needle That Rides on EddiesEM induction: eddy currents, Lenz, torque balance (eddy-current speedometer)Scholarship
Persistent Mode in the ScannerEM induction: self-inductance, LR decay, flux conservation (superconducting magnet)Scholarship
Reading the Ear TagAC: series LCR resonance, voltage magnification, detuning (RFID ear tag)Scholarship
Turning Down the Induction HobAC: series LCR resonance, power control by detuning, phase and energy exchange (induction hob)Bridge
The Lost NeutralAC: phasor addition, three-phase supply, unbalanced loadsScholarship
The Trailer With a Bad EarthDC circuits (shared return resistance, lamps in parallel, fault paths)Bridge
Two Substations and a GradeDC circuits (two sources feeding a load, constant-power load, voltage limit) with forces and powerScholarship
The Self-Regulating StraightenerDC circuits (non-ohmic PTC heater, power balance, self-regulation)Scholarship
Zapping the FlyCapacitors: parallel-plate capacitance and field, energy storage, RC chargingBridge
The Glucose Sensor's HiccupCapacitors: buffer capacitor, internal resistance, RC recovery, energy dissipatedScholarship
Catching Smoke on Charged PlatesCapacitors: parallel-plate field and energy, RC bleed discharge, with forces on charged particles (Stokes drag)Scholarship
The Loop Around the LoungeEM induction: field of a long straight wire, Faraday's law, telecoil pickupBridge
Thirty Milliamps in the BathroomEM induction: residual current device, flux in a toroidal core, Faraday's lawBridge
A Pulse Through the SkullEM induction: induced electric field from a changing magnetic field, LC discharge, inductor energyScholarship
Magnet ModeEM induction: Hall effect sensor, forces on moving charges, field of a magnet with distanceScholarship
Settling the Kitchen ScaleEM induction: eddy-current damping, Lenz's law, with damped oscillations of a spring-mass systemScholarship
The Buzz of the ClippersAC: RL impedance, power factor, rms power, with a resonantly driven spring-mass systemScholarship
The Bell in the Old PhoneAC: series LCR, reactance, DC blocking, resonance (telephone bell ringer)Bridge
Weighing the Woofer's ConeAC: parallel LCR equivalent of a moving-coil speaker, resonance, impedance peak, with SHM (added-mass method)Scholarship
Pumping to the Hill TroughDC circuits (emf, internal resistance, cable sizing, choice of supply voltage) with mechanical powerBridge
Counting Trout by ResistanceDC circuits (resistivity, series and parallel conduction, potential divider, common-mode cancellation)Scholarship
The Thermometer at the Bottom of the WellDC circuits (Wheatstone bridge, lead-resistance compensation, temperature coefficient)Scholarship
Earthing the Cable After the TestCapacitors: energy stored, RC discharge, insulation leakageBridge
Sharing the Strain on the Insulator StringCapacitors: series chains, charge conservation at isolated conductors, stray capacitanceScholarship
Power Down a Glass FibreCapacitors: constant-current charging and stored energy, with photon energy and photocurrent (power-over-fibre)Scholarship
Borrowing Flux from the LineEM induction: Faraday's law, alternating flux from a current-carrying conductor (energy harvesting)Bridge
Holding the Turbine Against the TideEM induction: generator emf, winding inductance (LR impedance) and braking torque, with rotational dynamics (tidal-turbine overspeed protection)Scholarship
Breaking a Direct CurrentEM induction: self-inductance, constant-rate current change, inductor energy (DC circuit breaker)Scholarship
Storm Currents in the National GridEM induction: Faraday's law over a large loop, quasi-DC induced currents in a network (geomagnetically induced currents)Scholarship
Exporting Through the InductorAC: inductive reactance, phasor addition, power transfer (grid-tied solar inverter)Bridge
The Capacitor That Shook the ShaftAC: series LC compensation, resonance, phasors, with torsional resonance (subsynchronous resonance)Scholarship
Ground Power at the GateAC: inductive reactance, impedance, power factor (400 Hz aircraft supply)Bridge
Running on Wild FrequencyAC: series LCR, power versus frequency, phase, design for a variable-frequency supplyScholarship

Waves · 77

Tuning the G StringStanding waves (strings, pipes, end correction, beats)Bridge
The Singing Sign on Cuba StreetStanding waves (strings, pipes, end correction, beats)Scholarship
The Warm and Cold KōauauStanding waves (strings, pipes, end correction, beats)Scholarship
Siren on State Highway 1Doppler (sound and light, moving observer/source, circular)Bridge
The Whirling BuzzerDoppler (sound and light, moving observer/source, circular)Scholarship
Pekapeka on the HuntDoppler (sound and light, moving observer/source, circular)Scholarship
Spots on the Lab WallInterference/diffraction (double slit, grating, thin film, Bragg)Bridge
Measuring Muka with an Air WedgeInterference/diffraction (double slit, grating, thin film, Bragg)Scholarship
Two Speakers on the WaterfrontInterference/diffraction (double slit, grating, thin film, Bragg)Scholarship
The Stopped Organ PipeStanding waves (pipes, harmonics, beats)Bridge
Two Resonances and an End CorrectionStanding waves (resonance tube, end correction)Scholarship
The Singing Brass RodStanding waves (longitudinal waves in rods, Kundt tube)Scholarship
Passing the Level-Crossing BellDoppler (sound, moving observer)Bridge
Spinning Sun, Shifted LinesDoppler shift of light (spectral lines)Scholarship
The Falling BuzzerDoppler (sound, accelerating source, travel time)Scholarship
Rainbow Glasses at the Street LightInterference/diffraction (diffraction grating, overlapping orders)Bridge
Sorting X-rays with SaltBragg reflection (X-ray crystal spectrometer)Scholarship
Steering the BeamInterference (two-source phased antenna array)Scholarship
Harmonics on the UkuleleStanding waves (strings, frets, harmonics)Bridge
Chocolate in the MicrowaveStanding waves (microwave oven, measuring c)Scholarship
Two Lines, One KnotStanding waves (composite string, junction node)Scholarship
The Fork and the WallDoppler (sound, moving source, reflection, beats)Bridge
Radar on the MotorwayDoppler (electromagnetic waves, radar, beats)Scholarship
The Ferry Horn in a GaleDoppler (sound in a wind, moving source)Scholarship
Laser Spots from a CDInterference/diffraction (reflection grating, optical discs)Bridge
The Cliff-Top Radio InterferometerInterference (sea-reflection radio interferometer)Scholarship
Standing Waves on a SlinkyStanding waves (longitudinal waves on a stretched spring)Bridge
Seiche in the SoundsStanding waves (shallow-water seiche, resonance)Scholarship
The Flared DidgeridooStanding waves (closed pipes, cylindrical and conical bores)Scholarship
The Singing SwingDoppler (sound, source moving on a pendulum)Bridge
Wind in the RainDoppler (electromagnetic waves, weather radar, velocity aliasing)Scholarship
Boom Over the PlainsDoppler (supersonic source, shock cone, sonic boom)Scholarship
Coating the Camera LensInterference (thin film, anti-reflection coating)Bridge
The Missing FringesInterference/diffraction (double slit with single-slit envelope, missing orders)Scholarship
Colours in a Draining Soap FilmInterference (thin film, soap film colours)Scholarship
The Boom in the Back SeatStanding waves (sound in an enclosed space, closed and open ends)Bridge
Tuning the Marimba ResonatorStanding waves (closed-pipe resonator, end correction, temperature)Scholarship
The Swaying Swing BridgeStanding waves (suspended span, cable tension and sag)Scholarship
Overtaken at PaekākārikiDoppler (sound, source and observer both moving)Bridge
Listening for the Tagged SharkDoppler (sound in water, moving medium, two receivers)Scholarship
Reading the PassDoppler (source passing at a distance, frequency–time record)Scholarship
Rings Under the LensInterference (thin air film, Newton's rings)Bridge
Cancelling the DroneInterference (active noise cancellation, time delay and phase)Scholarship
Beads in the Sound TrapStanding waves (ultrasonic levitator, pressure nodes)Bridge
The Bottle OrganStanding waves (closed pipe tuned with water, end correction, tuning sensitivity)Scholarship
The Ear's Built-in ResonatorStanding waves (ear canal as a closed pipe, sealed canal, temperature)Scholarship
Pressing SharpStanding waves (string tension change on fretting, Young's modulus)Scholarship
The Travelling DipperDoppler (water waves in a ripple tank, moving source)Bridge
Round the CornerDoppler (change of direction, component of velocity, emission versus hearing time)Scholarship
Music Through the DoorwayDiffraction (single slit, sound through a doorway)Bridge
Flutter from the Flight PathInterference (direct and aircraft-reflected radio waves, flutter, Doppler beats)Scholarship
Splitting the Sodium DoubletDiffraction grating (resolving power, sodium doublet)Scholarship
The Mains-Driven WireStanding waves (string driven by an alternating current in a magnetic field)Bridge
Hammer in the PenstockStanding waves (pressure waves in a water pipe, water hammer) with impulse and momentumScholarship
Modes of a LaserStanding waves (light in a laser cavity, longitudinal modes) with Doppler broadeningScholarship
Paddling Out at RaglanDoppler effect (moving observer, water waves, limiting cases)Bridge
Beats on the BikeDoppler effect (moving observer and moving source) with a two-source standing-wave patternScholarship
Listening to a CubeSatDoppler effect for electromagnetic waves (satellite pass) with circular orbitsScholarship
Splitting the PointerDiffraction at a circular aperture (resolving power, Rayleigh criterion)Bridge
Fringes from a Street LightInterference (double slit with an extended source, spatial coherence, stellar interferometry)Scholarship
Harmonics on the CelloStanding waves (string harmonics, forced node, stopped versus touched string)Bridge
The Quarter-Wave TrapStanding waves (electromagnetic standing waves on an open-circuit coaxial stub, notch filter)Scholarship
A Semitone on the BikeDoppler (sound, moving observer passing and braking past a stationary source, musical interval, limiting cases)Bridge
The Two-Faced Speed LogDoppler (sound in water, moving transmitter-receiver, echo from a stationary seabed, beam angle, pitch compensation)Scholarship
The Wobbling Flute NoteDoppler (source in simple harmonic motion, frequency modulation) with SHM of a loudspeaker coneScholarship
The Phone That Feels Your HandDoppler (echo from a moving reflector) with interference of direct and reflected sound (beats as path-length counting)Scholarship
The Column of SpeakersInterference (multiple in-phase sources as a grating for sound, grating lobes, beam width)Bridge
Tuning the Fibre MirrorInterference (multiple reflections from a periodic structure, fibre Bragg grating, selectivity) with elasticity (strain tuning)Scholarship
Counting the Growth of an AlloyInterference (Michelson interferometer, fringe counting, refractive index of heated air)Scholarship
Plucking the Rudder CableStanding waves on a string (control cable tension from frequency, harmonics and pluck point)Bridge
Pogo on the Way UpStanding waves in a pipe (closed–open feed line) with mass–spring SHM: pogo resonance in a rocketScholarship
A Tether Pulled Taut by GravityStanding waves on a string with tidal tension from orbital motion (tethered satellites)Scholarship
Bouncing Signals off the MoonDoppler effect for reflected radio waves (Earth–Moon–Earth echoes, transmitter carried by Earth's rotation)Bridge
Riding a Laser BeamDoppler shift of light reflected from a moving mirror, with photon momentum and energy conservation (laser sail)Scholarship
Propeller Flashes on the RadarDoppler effect for radar echoes from rotating blades (micro-Doppler) with circular motionScholarship
Rings Round the MoonDiffraction by small circular obstacles (lunar corona from cloud droplets)Bridge
Measuring an Earthquake from OrbitInterference of radar echoes from two passes (satellite radar interferometry), path difference and refractive indexScholarship

Modern Physics · 89