Measuring g by Freefall QuantumBoffin 2021-07-04 | This video demonstrates an experiment to measure the value of g - the Earth's gravitational field strength at sea level.This is achieved by dropping a small ballbearing from a variety of heights and timing how long it takes to fall. This is achieved using an electronic timer, a small electromagnet, a piezo electric pad and an interface box.The equipment was produced by a friend of mine, but commercial versions of the apparatus are available from various educational suppliers.To calculate g one must use the equation:h = 1/2 g t^2(where h is the height, g is the gravitational field strength and t is the time).This can either be done by calculating g for individual results and taking an average, or by plotting a graph of 1/2 t^2 (y-axis) against h (x-axis) and adding a best fit line: The gradient of the line then gives the value of g.
The Specific Heat Capacity of Water QuantumBoffin 2021-06-27 | The specific heat capacity of a solid is the energy required to raise the temperature of 1 kg of that solid by 1 degree Celsius.In this video I demonstrate a simple experiment to determine the specific heat capacity of water, using a simple electric heater.The value obtained is much greater that the actual value: This will always generally be the case, as much of the heat that is added to the water is lost to the surroundings.Points to consider:What steps were taken to reduce heat loss?How could the experiment be improved to further reduce heat loss?
The Time Period of a Pendulum QuantumBoffin 2021-06-20 | The time period of a pendulum only depends on two things: The gravitational field strength (which is approximately constant, here on Earth) and the length of the pendulum.It does not depend on the mass of the pendulum or the amplitude of the oscillations (well... for small oscillations, anyway.... but that's a different experiment).In this video I demonstrate how the time period changes with length. The pendulum is allowed to oscillate a number of times for each length: The time period can be found by measuring the time for, say, 10 oscillations, and then dividing that time by 10.The results from this experiment can actually be used to calculate the gravitational field strength:Plot a graphs of the length in metres (on the y-axis) against time period squared (on x-axis).The gradient of the resulting graph is equal to the gravitational field strength divided by (2 Pi) squared.
Demonstrating the Photoelectric Effect QuantumBoffin 2021-06-13 | The photoelectric effect concerns the emission of electrons by ultraviolet light.In this video I give a quick demonstration of this phenomenon using a gold leaf electroscope, a zinc pate, an EHT power supply, a high intensity (visible) light source and an ultraviolet lamp.I start by giving the zinc a negative charge (so that it has an excess of electrons) and expose it to first the visible light and then the uv light.Next I give the zinc a positive charge (so that it has too few electrons), repeating the exposure.This second part of the demonstration (using the positive charge) is rarely performed by teachers, in my experience, and yet (in my opinion) is a very important part of the demonstration. Many people forget the importance, at times, of noting what fails to happen alongside what does happen.
The Emission of Thermal Radiation QuantumBoffin 2021-06-06 | In this experiment I demonstrate how the colour of a hot object affects the amount of thermal radiation emitted by that object.The two flasks are identical in all ways except for their colour. They are both filled with equal quantities of hot water at the same temperature.The main way in which the flasks lose heat is through the processes of conduction and convection, but the black flask also loses an appreciable amount of heat due the emission of thermal radiation, as can be seen by comparing its temperature to that of the shiny flask.
The Absorption of Thermal Radiation QuantumBoffin 2021-05-30 | This simple experiment provides a quick demonstration of the effect of colour on the absorption off thermal radiation.Two identical beaks are painted different colours: One shiny, the other black. They are then placed equal distances from a filament lightbulb (a source of thermal radiation).Thermometers placed in the top of each flask allows the temperature to be monitored.
Measuring Density QuantumBoffin 2021-05-23 | Density is the mass per unit volume of a substance.In this video I demonstrate three methods for measuring the density of different substances.I start by demonstrating how to measure the density of a liquid (water, in this case).I then measure the density of a regular solid (an aluminium cube), by measuring its dimensions.Finally I look at an irregular shape (a lump of lead), using a eureka (archimedes) can to measure its volume.The top pan balance measures the mass in grams. The flickering of the readout is caused by "aliasing", which is due to the frame rate of the camera being slightly different to the refresh rate of the digital display. I edited the video to try and minimise this effect.
Starting a Fire using a Parabolic Mirror QuantumBoffin 2021-05-16 | Thermal Radiation, in the form of Infra Red, is closely related to visible light and can be brought to a focus using a simple parabolic mirror.In this demonstration I show how this focusing effect can be used to start a small fire.I apologise for a slight continuity error in terms of my clothing. When reviewing my original footage I found a slight problem, so decided to refill part of the video (mid way through a cycle ride!)
The Specific Heat Capacity of Aluminium QuantumBoffin 2021-05-13 | In this video I demonstrate an experiment to determine the specific heat capacity of aluminium.There are several ways of processing the data: One is just to determine the total energy added (current x voltage x time) and then divide it by the mass and the total change in temperature.A better method is to take the time at which the temperature reaches two specific values (e.g. 20 degrees and 30 degrees) and then use those times to determine the energy added.Alternative, a graph of temperature against time can be plotted: The specific heat capacity is then relative to the reciprocal of the gradient - for the best value, look for the steepest gradient section.The experiment has a number of inaccuracies: The main one (heat loss) means that the value obtained is always greater that the actual value. You might like to think of ways in which the experiment could be improved.You may also notice, it takes a while for the temperature on the thermometer to start increasing. This is because it takes a little while for the heat to spread through the block. For this reason, I left the experiment running after turning off the power supply, to give the final bit of heat time to reach the thermometer.You may also notice a small systematic error with the ammeter: For some reason, at the end of the experiment, it continued to read "0.04A" even though there was no current. I'm not sure why this was, as it worked earlier on, although by the time I set the apparatus up it was already reading "0.01A".Finally, I'm sorry about the reflections from the thermometer, which can make it a little hard to see the temperature at times. I didn't notice these at the time of recording, as they only became apparent when I zoomed in on the video afterwards.
Ray Diagrams: Diverging Lenses QuantumBoffin 2021-05-06 | A diverging lens ( also known as a concave lens) is one that causes light passing through it to diverge away from a focus. This can result in the formation of a virtual image.In this video I explain the rules that can used to draw lens ray diagrams for diverging lenses and demonstrate the construction of one such diagram
Making a Poster using Microsoft PowerPoint QuantumBoffin 2021-05-02 | PowerPoint can be used for of lot of things as well as making sideshows. In particular it is excellent for making posters, having many of the tools that are available in packages such as Publisher.Furthermore, unlike Publisher, PowerPoint is available on a variety of platforms, including Macs.In this video I demonstrate how to create a quick poster.The topic of my chosen poster is "The Lifecycle of Stars" - a topic I often get my pupils to turn into posters when studying that area of Physics.
Ray Diagrams: Converging Lenses QuantumBoffin 2021-04-29 | A converging lens (also known as a convex lens) brings light to a focus, resulting in the formation of a real image (an image formed by the convergence of rays of light).In this video I explain the principles behind drawing lens ray diagrams for converging lenses and then demonstrate the drawing of two such diagrams:The first where the object is further from the lens than the focus.The second where the object is closer to the lens than the focus.
Ray Diagrams: Reflection QuantumBoffin 2021-04-25 | In this video I explain how to draw a ray diagram for light reflecting from a plane (flat) mirror and show how it can be used to find the position of the object.At the end of the video I give some extra tips as to how you can draw a ray diagram quickly and accurately in an exam - so make sure you watch all the way to the end!
Newtons Second Law: Experiment QuantumBoffin 2021-04-07 | Newton's second law concerns the relationship between the resultant force on an object and the object's acceleration.In this video I present an experiment to investigate this relationship. Some small masses are used to accelerate a trolley along a low friction track. The acceleration of the trolley can then be determined using the data from two photogates, which give the trolley's initial velocity, final velocity and the time taken. The acceleration can then be found using the formula:acceleration = (final velocity - initial velocity)/time takenSome points to note:1) You will notice that one of the readings from the experiment failed to record correctly. I didn't spot this until later, when I came to edit the video. I decided to leave the "anomaly" in the video rather than going back and retaking the measurement.2) I have used the approximation that g = 10 N/kg, although you may prefer to use the more accurate value of 9.83) An analysis of the data gives a value for the trolley mass that is too small. This is because the calculated accelerations are (surprisingly) slight too large. This is due to the way in which the photogates measure the time taken for the trolley to pass between them, which give a value for the time taken which is slightly too small.This can be corrected for by either:a) multiplying the time figures by about 1.05.b) calculating the acceleration using the (slightly more advanced) formula:v^2 - u^2 = 2aswhere s is the distance between the photogates, which was approximately 0.33m
The Deflection of Beta Particles QuantumBoffin 2021-03-31 | TURN YOUR SOUND UP!This radiation detector in this video makes clicking noises to indicate the presence of radiation: You will need to have your sound on in order to follow the video.Beta particles are emitted from certain unstable nuclei. When passes through a magnetic field, they are deflected in accordance with the Left Hand Rule (the motor effect). This video demonstrates this effect. The results can be show to be consistent with the charge of the beta particles.You will notice that during the video I use tongues and a clamp to avoid getting too close to the radioactive source. I also minimised the time for which I was using the source and kept it in a lead lined container when not in use.I realised, after editing the video, that at times it looks as though one of my hands is passing very close to the beam. Thankfully this was not the case - I was careful to keep both of my hands out of the beam at all times.
Boyles Law: An alternative method QuantumBoffin 2021-03-26 | In an earlier video I demonstrated Boyle's law using some specialised equipment, consisting of a tube a air, trapped (and compressed) by a column of oil.In this video I demonstrate a simpler version of the experiment: Compressing the gas using an air filled syringe connected to a digital pressure gauge.Readings of pressure and volume can be taken from the video allowing an analysis to be carried out.It should be noted that there is a significant systematic error in one of the readings, which I explain at the end of the video. I will pin a comment to the video giving a corrected figure, but some of you might wish to use the data to calculate the figure yourselves.When carrying out the analysis I suggest plotting a graph of 1/P (y-axis) against Volume (x-axis). Make sure you leave some room to the left hand side of your y-axis(if using the raw data): You may well see the reason for this when you plot your graph.
The Pressure Law: Heating a gas at constant volume QuantumBoffin 2021-03-22 | The pressure law describes the relationship between the pressure of a gas and its temperatures, when the gas is kept at a fixed volume.This video demonstrates an experiment to investigate this relationship, allowing results to be taken from the video.A few comments:First of all, you will notice that the computer gives a silly number of significant figures. I should have got it to round the numbers down to a more appropriate level.The video was recorded using time lapse. The experiment was actually carried out over a period of about 30 minutes.You will also notice that the temperature rises quickly to begin with and then tails off as it gets hotter: This is because the apparatus is losing heat to the surroundings. I struggled to get temperatures above 66 degrees celsius and so had to turn up the bunsen flame towards the end of the experiment.The results can be used to estimate the value of absolute zero. I've found that the experiment always seems to give too high a value (I got about -260, based on the data in the video) - not sure why. If you have any thoughts, please let me know in the comments. For a more accurate estimate of absolute zero I recommend watching my video on Charles' law.
Dropping a magnet down a copper tube: A demonstration of Lenzs law. QuantumBoffin 2021-03-20 | A simple demonstration of Lenz's law and the principles of Electromagnetic Inductions.I realise that during my explanation I state that a current is induced in the copper tube. Strictly speaking this is not true: The motion of the magnet induces an EMF (a potential difference) and it is the EMF that drives the current. I wanted to keep my explanation quite simple, though, and so avoided talking about EMFs as I felt this could confuse some viewers.
Charles Law: Heating a gas at constant pressure QuantumBoffin 2021-03-13 | An experiment to demonstrate Charles' Law - the behaviour of a gas when heated at constant pressure.The experiment features a glass capillary tube that is sealed at one end and has a mercury thread at the other, which is able to move along the tube when the gas expands.The tube is heated in a water bath: A scale allows the volume of the gas to be measured and a thermometer shows the temperature in celsius.Apologies for the shaky camera work. The video was taken in time lapse (actual time for the experiment was around 30 minutes) and it was necessary to move the camera to give clear shots of the mercury thread and thermometer.Some of you may want to think about two sources of error: Parallax and the fact that some of the gas column sticks out above the water line. Despite these sources of error, I found that the data from the experiment have a pretty good measurement of absolute zero.
Investigating Magnetic Field Lines with a Compass QuantumBoffin 2021-03-08 | A simple experiment demonstrating how a compass can be used to investigated the magnetic field patterns around a bar magnet and a current carrying wire.
Simulating Radioactive Decay QuantumBoffin 2021-02-28 | Radioactive decay is a random phenomena, meaning that the decay of an individual nucleus is unpredictable.In this video I demonstrate a simple experiment to simulate decay, using dice. Each die represents an individual nucleus. Each time the dice are shaken any 6s represent nuclei that have decayed, whereas other numbers represent nuclei that are yet to decay.In this way, we can simulate the change in number of nuclei (and activity) over time, leading to a better understanding of radioactive half-life.
Boyles Law QuantumBoffin 2021-02-22 | A demonstration of Boyle's law of gases: The relationship between the pressure of a gas and its volume (for a fixed quantity of gas at a constant temperature.The tube in the video contains a fixed quantity of gas, the volume of which can be measured against a scale. A for pump is then used to apply pressure to the gas (which can be measured using the needle on the meter), compressing it.Pause the video to take readings. The results, whilst not perfect, do a good job of illustrating Boyle's law.
Making a Simple DC Motor QuantumBoffin 2021-02-18 | This video demonstrates how to create a simple DC electric motor using a few simple bits and pieces. The parts I use in the video come from a Westminster Motor Kit - a search for this term should bring up a list of suppliers.I realise that at one stage in the video my hands cover the workings of the motor: During this stage al I am doing is holding the wires vertically so that they brush against the two wires coming from the coil (at either side of the axle).The large motor I demonstrate at the end was constructed by a colleague of mine who assembled it using a variety of odds and ends that he had lying around.
Plotting Magnetic Field Lines QuantumBoffin 2021-02-17 | A simple experiment demonstrating how iron filings may be used to plot field lines around:A single magnetTwo magnets (repelling)Two magnetic (attracting)A current carrying wireA current carrying solenoid (a long coil)The basic technique is:Cover the magnets with paper (or place paper in the area you will be scattering the filings)Gently shake a few iron filings on to the paper.Tap the paper gently to help the iron filings settle into a pattern.The field line for the current carrying wire are very faint and difficult to see. This is because the field that is produced is very weak. If you look carefully, though, you may be able to make out some concentric circles going around the wire.
Fuse Wire QuantumBoffin 2019-07-04 | A short video demonstrating some fuse wire in action.A fuse is a simple component designed to cut off the supply of electricity to a device if the current becomes too large.It does this by melting, which breaks the circuit, stopping the current.
Refraction through a rectangular block QuantumBoffin 2019-07-02 | Another demonstration of Snell's law, this time using a rectangular block. The method demonstrated is the one required by various examinations boards including Edexcel, for their IGCSE Physics qualification.For an alternative version of this experiment (using semi circular blocks) click on the link below.youtube.com/watch?v=yfawFJCRDSE&t=4s
Gamma Required Practical QuantumBoffin 2017-04-23 | This is a demonstration of the A level Physics Require Practical (for English examination boards): Investigation of the Variation of Intensity of Gamma Radiation with Distance.
IV Characteristics of a lamp and a wire at constant temperature. QuantumBoffin 2017-04-21 | This is a demonstration of the A level Physics Require Practical (for English examination boards): IV Characteristics of a filament lamp and a wire at constant temperature.
Thermal Radiation and Leslies Cube QuantumBoffin 2016-05-10 | Leslie's cube is a classic demonstration of the emission of thermal radiation. The cube is heated to a uniform temperature by filling with water. The side of the cube are painted different colours: Shiny, matt, white and black.In this video a thermal imaging camera (FLIR ONE) is used to view the Infra Red (thermal radiation) emitted from each of these surfaces.
The Exploding Capacitor QuantumBoffin 2014-12-01 | Some types of electrolytic capacitor have polarity. This means that one of its terminals must be connected to the positive side of the power supply. If connected to the wrong terminal the results can be catastrophic.
The Monkey and the Hunter QuantumBoffin 2014-10-10 | The classic demonstration of projectile motion.A hunter sets out to shoot a monkey. The monkey thinks he can avoid the hunter's rifle bullet by dropping from the tree, but will his strategy work?
The Astronomical Telescope QuantumBoffin 2014-07-08 | An explanation of how to draw a lens ray diagram for an astronomical telescope, including a quick derivation of the formula for angular magnification.
Cloud Chamber - Extended (ambient) footage QuantumBoffin 2014-03-23 | Extended footage showing alpha particle tracks from a plutonium source in a Lascells Thermoelectric Cloud chamber.Use the footage as the backdrop to a lecture, talk or lesson on radioactivity.
The Cloud Chamber QuantumBoffin 2014-03-22 | A simple radiation detector allowing you to see the ionisation trails left by radiation.Thoriated welding rod contains small amount of the radioactive element Thorium - an alpha emitter.The alpha source is Plutonium. The short range of the alpha particles can clearly be seen.The beta source is Strontium. The beta particle create much finer trails and speckles - a result of their lower ionising power.
The Fire Piston QuantumBoffin 2013-12-18 | A demonstration of the ignition of a flammable material by the process of doing rapid work on a gas.This process lies at the heart of the workings of Diesel engines and is an important demonstration of thermodynamic processes.
Breaking Glass Fibres QuantumBoffin 2013-06-13 | This is one of my all time favourite experiments!You start by creating a hook in the end of a short length of soda glass (look for the colour of the flame!) A mass is then attached and the glass is heated until it starts to stretch (stop heating as soon as it has fallen about 10cm).Masses can now be attached to the glass fibre to find the breaking force and the diameter measured at the break point using a micrometer. Once these are known, the breaking stress can be calculated using the formula:Stress = Force/AreaMy values were:Max mass = 400g (force = 3.92N)Diameter = 0.21 mmPlease note:The glass in this experiment gets extremely hot and stays hot for a long time. Please take care when handling.The ends of the glass are extremely sharp and fragments can be scattered widely when it breaks. Make sure you wear safety goggles at all times.Finally, I would love to see some videos showing the longest fibre you can create - if you try this out, please post a video response to my video!
Plotting good Science gaphs in Excel (2007 onwards) QuantumBoffin 2013-05-16 | A tutorial showing how to plot a good quality graph, suitable for Science, using the more recent versions of Excel (2007 and 2010 for Windows; 2008 and 2011 for Mac).The video demonstrates how to select data,; swap the axis; add chart and axis titles; add gridlines; edit the scale; format the data points.
Plotting Science Graphs on the iPad QuantumBoffin 2013-05-13 | A demonstration showing how a simple graph may be plotted on the iPad using a combination of Apple's Numbers app and Notability. Numbers is used to plot a scatter graph of some exemplar data before exporting the graph to Notability, the popular note taking app. Notabilities features are then used to add a trendline to the graph.
Simple Graph Plotting on Excel (Energy Resource data) QuantumBoffin 2013-05-13 | A demonstration of how to carry out simple calculations and graph plotting using Excel. The tutorial uses Historical Electricity Production data to produce graphs showing the change in energy production between 1920 and 2011. This data is freely available online.The tutorial uses Excel 2011 for Mac, but the techniques demonstrated can be applied to any version of Excel which features the "Ribbon" interface (e.g. Excel 2007 onwards, PC and Mac versions).
Total Internal Reflection QuantumBoffin 2012-01-13 | An experiment demonstrating the total internal reflection of light inside a glass block. An angular scale is provided allowing the critical angle of the glass to be measured and the refractive index of the glass to be determined.
Digital signals QuantumBoffin 2011-12-13 | Digital information exists all around us, but what happens to our music when it becomes digital? This video demonstrates how analogue waves may be converted into digital signals via a process known as pulse code modulation. issues such as aliasing and noise are examined along with their implications for the process of sampling an analogue wave.
The Jumping Ring QuantumBoffin 2011-11-18 | An Aluminium Ring is placed on top of a coil. When an alternating current is supplied to the coil the ring floats.
Van de Graaf SnowStorm QuantumBoffin 2011-11-17 | Small pieces of paper are placed on top of a Van de Graaf generator. The generator repels the paper causing a snowstorm effect.
Standing Waves on a string QuantumBoffin 2011-06-28 | Standing waves are produced on a length of rubber cord using a vibration generator attached to a digital signal generator. The frequency is steadily increased and the frequencies at which the various standing wave patterns form are noted down.
Heisenbergs uncertainty QuantumBoffin 2011-06-23 | Physics Joke about Heisenberg's uncertainty principle
vacuum flask joke QuantumBoffin 2011-06-23 | Physics Joke - what s the greatest invention of all time? the vacuum flask...
