Physics 

What is ‘Tensile Testing’?

The ‘tensile’ properties of a material describe its most basic mechanical behaviour – how much does a material stretch when it is pulled and how much of the stretching is permanent? ‘Tensile Testing’ is the process of measuring a material’s tensile properties. 

Why are tensile properties important?

Understanding of tensile properties is vital for any application that uses materials structurally, i.e. to withstand or apply force. The range of uses this covers is enormous. Strong and stiff structures are used in vehicles (cycles, cars, trains, aeroplanes, spacecraft), bridges and buildings, sports equipment and bio-implants (e.g. hip joint replacements). Flexible materials are also used in many of these applications. Thin but robust materials are used in touchscreens. Hard materials are used in machines and robots that process and shape other materials and as durable coatings that improve the performance and lifetime of aerospace and bio-implant components. Elastic materials can be stretched enormously before any permanent change is made and are used in springs and high performance fabrics. And it’s not just how a component is used – many manufacturing processes involve changing a component’s shape or response to applied forces, e.g. extrusion to make tubes, beams and bottles; drawing to make springs or wires; or forging and rolling to shape and harden metals.

To select a sample:

• Click the lower jaw to go to the sample view.
• Open the calliper jaws, drag a sample of choice between the jaw and fully close the jaws around it. In this LITE version you can only select one of the samples)
• Use the Vernier scale to measure the sample width.
• Click the sample held in the callipers to use it in the tensile testing machine
• Or open the callipers, return the sample to its original position and choose another sample. (Only available in the full version)

To set the strain increment:

• Click the Set button (display starts to flash)
• Use the keypad and the Del button to enter the desired Step value
• Click the Set button again (display stops flashing)

To apply strain to samples:

• Set the strain increment value as described above.
• Click the up arrow to increase the applied strain by the Step increment value.
• Click the down arrow to decrease the applied strain by the Step increment value.
• Measure (and record) the applied load (force) using the needles on the Load dial.
• Turn off the strain control unit and click on the lower sample holder to select a new sample.

These instructions can be downloaded below.

Download the file below for the full instructions, including background, relevance, operating instructions and questions.

Structural materials are required to withstand a variety of applied loads in use. Understanding how these materials respond to the applied loads is vital for informed materials selection. Here we investigate how materials behave under tensile loading (loads applied along the length of a material to cause stretching).

The Tensile Test experiment allows a number of mechanical tests to be performed on materials, including:

• Determination of full stress-strain curve to fracture, using either ‘engineering’ or ‘true’ value
• Observation of elastic behaviour and calculation of Young’s modulus
• Observation of the onset of plastic behaviour and permanent deformation
• Calculation of moduli of resilience and toughness
• Calculation of strain energy in a system
• Calculation of work done in deforming a sample

The Tensile Testing experiment can be used for a wide range of investigations.

This downloadable pdf below contains a range of example short and long questions.

We have also provided a spreadsheet file to allow you to enter your SAMPLE WIDTH, STRAIN and APPLIED LOAD data and obtain stress-strain plots. (HINT: to investigate the general form of stress-strain curves with younger students, use a default sample width of, say, 7 mm)

Watch the video and download the file below to learn about the scientific background of Tensile Tests

Ohm’s law

Voltage, current and resistance are the most fundamental quantities for describing the flow of electricity. Ohm’s law shows how these three quantities are related and so is a powerful way of understanding the basic nature of electricity.

This is relevant to vast areas of technology today, including national electricity grids, power generation, design of all electronic devices and all electronic circuits, heating, electrical safety and understanding of natural phenomena such as lightning. This experiment will allow you to explore Ohm’s law by making measurements of voltage, current and resistance.

Resistors

Resistors are the simplest and most commonly used electronic component and almost all electronic circuits them. They can be used to change the properties of any circuit they are part of, such as current flow, how voltage is distributed across components, the speed of a circuit, the amount of amplification from a circuit, the response of a sensor or the amount of electrical heating from a circuit.

The simplest resistors are made of a thin film or wound wire of carbon or metal. They usually have a series of coloured bands that represents both their target resistance value and how much the actual value might vary from this (the ‘tolerance’). This experiment lets you practise selecting the appropriate colour bands on a resistor to achieve a certain resistance value.

Digital Multimeters

Digital multimeters (DMMs) are versatile pieces of equipment commonly found in electronics, physics and engineering labs. In this experiment you’ll learn how to use a DMM to measure voltage, current and resistance. You’ll see this piece of equipment in many other FlashyScience experiments!

Download the attached file for the Quick Guide including a table of resistor colour bands (requires log in) or follow these instructions:

To measure resistance:

• On the right-hand Digital Multimeter (DMM) rotate the switch to resistance measurement
• Click and drag the clips on the wires attached to the right-hand DMM so that they snap to the wires either side of the resistor (make sure the power supply is turned off)
• Note the resistance value shown on the DMM screen

To change the resistor:

• Click the resistor you wish to change to move to the Selection screen
• Click on the colour band you wish to change
• Click on the palette colour you wish to select
• Click on the resistor wire to return to the main screen

To use voltage and current:

• Turn on the power supply (right hand side of screen) and turn the dial to set the voltage
• To measure current through the resistor – turn the left-hand DMM dial to DC current
• To measure the voltage across the resistor – turn the right-hand DMM dial to DC voltage
• NOTE: in this experiment the power supply voltage is also shown directly on its display

​Please download the attached file for full operating instructions of the Ohm’s Law experiment (requires log in)

​See attached file for questions on the experiment (requires log in)

​Download attached file to see background information for this experiment (requires log in)

It is safe to say that gravity is important to us! Without gravity there would be no life on Earth and, in fact, without gravity, the Earth would never have existed.

Gravity is responsible for stars forming in the first place, keeping the Sun from exploding from the heat it generates, and for the structure of galaxies. It also keeps the Earth in orbit around the Sun, keeps our atmosphere and oceans in place and means we don’t float off into space. Gravity even allows plants to detect which was is ‘up’ so they send their roots and shoots in the right directions. You can see more at this NASA web page.

So, why does it matter that we know how strong gravity is?

Well, for lots of reasons.

The strength of gravity is essential to know in Civil Engineering projects such as design of
buildings and bridges so we can calculate the stresses materials are under.

Aircraft and space rocket designers must know the strength of gravity that must be overcome and satellite technology is based upon a certain strength of gravity to maintain orbits at particular heights above the Earth.

Hydroelectric power generation also relies on gravitational potential energy, either through energy ‘storage’ in dams or from the water flow or tides in rivers or oceans.

Our quality of life would be very different too. Most sports rely on gravity (we’re not counting chess as a sport here!) and gravity even keeps food in a saucepan while it cooks!

​Download the one-page guide through the link to see how to operate the Free Fall experiment (requires log in).

Basic operation is as follows:

• Choose between using a Pressure Pad sensor and Light Gate sensors using switch on side of timer
• If using Pressure Pad sensor:
  • Click and drag the electromagnet 
  • Read the height of the ball on the electromagnet using the magnified view of the ruler
  • Press the Start/Reset button to release the ball from the electromagnet
  • Read the time (from the timer) for the ball to drop to the pressure pad
  • Press the Start/Reset button to return the ball to the electromagnet and reset the timer to zero
• If using the Light Gates:
  • Click and drag the electromagnet and both light gates to adjust their height on the ruler but ensure the separation of the electromagnet and first light gate is constant throughout your experiment
  • Measure the distance between light gates using the magnified view of the ruler
  • Press the Start/Reset button to release the ball from the electromagnet
  • Read the time for the ball to fall between the light gates
  • Press the Start/Reset button to return the ball to the electromagnet and reset the timer to zero

Measured Earth’s gravity? Click on the poster to explore gravity elsewhere in the Solar System too!

Click on the link to download the full operating instructions for the Free Fall due to Gravity experiment (requires log in)

​Click the link to download a file with four example experiments (requires log in). These are:

Exp 1. Measurement of g using pressure pad sensor

Exp 2. Measurement of g using light gate sensors

Exp 3. Travel the Solar System!

Exp 4. Uncertainty in g based on uncertainty in individual measurements

Click on the link to download a file that explains how to calculate acceleration due to gravity (requires log in). This also describes ways of determining and combining uncertainties in experimental measurements .

Radioactive elements (radionuclides or radioactive isotopes) produce high energy particles and are used in a huge range of applications. Most people know about nuclear power, which converts the energy of radiation from uranium-238 or plutonium-239 into heat and then electrical power, even in small-scale form for remote applications (e.g. spacecraft). There are far more widespread uses all around us though.

Radionuclides are used in many medicinal applications. They can be used as tracers to follow fluid flow inside the body by detecting the radionuclide emitted radiation (e.g. technetium-99, thallium-201, iodine-131 and sodium-24). Medical imaging can use radioactive elements that naturally collect in particular parts of the body and image the radioactive emission. For example, iodine-131 is used to image the thyroid and other isotopes can be used for other organs, such as bones, heart, liver and lungs. Larger doses of the radionuclides (e.g. cobalt-60) are used to create a targeted radiotherapy treatment of cancer in these organs. It is even possible to detect the presence of Heliobacter pylori (an unwanted bacterium that can be in stomachs) with a simple breath test that uses carbon-14.

You may have radioactive materials in your home, school or workplace. Smoke detectors use alpha radiation from americium-241 to ionise smoke particles for detection. Glow-in-the-dark inks on clocks, watches and emergency signs that convert radioactive particle energy from promethium-147 into light.

You may also have food that has been treated with radiation. Many foods (including tomatoes, mushrooms, berries, cereals, eggs, fish and some meat products) are irradiated with gamma rays from cobalt-60 to kill micro-organisms and improve the food’s shelf life (without making the food radioactive!). Similarly, gamma radiation from caesium-137 is used to sterilise medical products such as syringes, heart valves, surgical instruments and contact lens solutions.

Radioactive elements are used in industry too. For example, the absorption of different types of radiation mean it can be used to monitor the thickness of manufactured components and sheets. Radionuclides are also used for detecting leaks from pipes, the direction of underground pipes and waste dispersal in the environment. Radioactive sources are also used in industrial imaging, with the sample placed between the radiation source and a detector. Certain isotopes are used as chemicals in order to trace chemical reaction routes, e.g. carbon-14 in photosynthesis. Similar approaches are used in biology to test when proteins undergo important ‘phosphorylation’ reactions (using phosphorus-32) to learn when their function is activated by other proteins or small chemicals.

Radioactive elements can also be used for historical dating of objects, e.g. carbon-14 dating for estimating the age of organic matter and uranium-238 for rocks. Similarly, radioactive decay from vintage drinks such as wine can be used to prove their age, since radionuclides were released into the atmosphere by nuclear explosion tests after World War II and are present in all food and drink produced since then.

With so many uses, it’s no wonder that radioactive decay is an important aspect of science and engineering!

Download the attached file to see the full Quick Guide (requires log in) or follow the instructions below:

Select the radiation source:

• Click on the Source holder
• Click on one of the radiation sources in the tray and then in the holder

Detecting radiation:

• Click the power switch on the Geiger-Müller counter.
• Read the needle position on the dial to measure level of radiation.

Changing the filter material and thickness:

• Click on the filter holder
• Click on the material of choice to increase its thickness in the holder by 1 mm
• Click on the material in the holder to reduce its thickness by 1 mm
• Measure the filter thickness using the markings inside the holder

Change the source-detector separation:

• Click and drag the holder mount to move it along the ruler
• Measure the mount’s position using the magnified ruler view seen while clicked on the holder mount.

Time travel!

• Move time forward by one minute, hour, day, month or year by clicking on the appropriate value on the clock

Open the file below to see the full instructions for operating the Radiation experiment (requires log in):

Download the file below to see example experiments, including for GCSE and A-level (requires log in).

Or see if you can do some of the following:

• Measure the half-life of different sources (GCSE)
• Measure how detected gamma radiation varies with source-detector separation
• Find out how alpha, beta and gamma radiation is absorbed by various materials
• Explore multi-decay type radioactive sources

Download the file below to see the scientific background of radioactive decay (requires log in)

Electronic materials are crucial to our life today, and electrical ‘resistivity’ tells us how good or poor a material is at conducting electricity.

We use materials with low electrical resistivity to transmit electrical power from generators, across grid distribution networks, and to homes and workplaces for use. Designers of electrical devices rely on knowing the resistivity of wire used in order to calculate the resistance of components.

These devices range in size from enormous machines such as wind turbines or industrial lifting equipment; motors or engines in electric vehicles and all-new electric aircraft; consumer products such as washing machines, hair dryers and ovens; and the nanoscale components within the computer chips found in smart devices, laptops, and mobile phones.  

In fact, modern computing is based on controlling the resistivity of semiconductor materials in a type of transistor (known as ‘field effect transistors’ using ‘CMOS’ technology).

Measuring electrical resistivity helps us to understand the properties of materials, to monitor manufacturing processes, and to select the best material for an application.

Click on the link below to download the Quick Guide for using the Resistivity experiment. Or follow the brief instructions here:

1. Click on the right hand wire post to move to the Select Wire screen.
2. Open the micrometer by dragging the thumbwheel down.
3. Choose a material and drag the unlabelled wire into the micrometer.
4. Close the micrometer and measure the wire's width.
5. Click on the wire while it's in the micrometer to return to the main screen.
6. Click on the switch to turn it on.
7. Measure voltage and current for a variety of contact positions on the wire.
8. Calculate resistance for each contact position. 
9. Plot resistance vs contact position and calculate the gradient of a line of best fit.
10. Multiple the line's gradient by the wire's cross-sectional area to obtain the wire's electrical resistivity.

Click on the link to download a pdf of the Instructions for operating the Resistivity experiment

Click on the link below to download a pdf of example questions for the Resistivity experiment.

Click on the link to download the Background pdf for the Resistivity experiment.

Stretching – the truth!

You may wonder why we study springs and why questions about stretching springs appear on exams. Sure, springs are used in the world, but are they really so important? Why is it important to know how springs stretch when they are pulled?

Well, first, springs are incredibly useful. When made from elastic materials, such as most metals, springs stretch when pulled and return to their original size when released. They can also be compressed and, again, return to their original size when released. The stretching or compression stores energy that is then returned when the spring is released. This energy storage and return is the key reason springs are useful. Springs use this capability in all sorts of applications, including in high tech areas such as automotive, industrial tools and robotics, to more everyday items such as trampolines, mattresses, children’s play equipment, door handles and retractable pens. 

The second reason is that the way that springs respond to force being applied to them (i.e. being pulled or mass added to one end of them) is identical to how materials in general behave. If materials are pulled, then they stretch. The coiled shape of a spring, though, means that the ends tend to move large distances compared to a regular shape of the same material (e.g. a simple rod). This means that studying what happens to springs when they are pulled allows simple measurements to be performed that give us understanding of how all materials behave when they are pulled. Materials behave this way in any application where they have force applied to them, e.g. in construction, vehicles, heart valves, body implants, plants, rocks, furniture, tools, footwear – the list goes on and on. And don’t forget this includes your body too!

Use this experiment to find out more!

Follow these instructions or download the Quick Guide via the link (requires log in):

1. Click on 50 g or 100 g masses to add them to the mass holder.
2. Click on the ruler to go to a zoomed view (centimetre scale).
3. Click on the masses on the holder to move them back to their boxes.
4. To change to a different spring:

• Remove all mass from the holder.
• Click on the spring.
• Select from Low, Medium, High or Unknown Stiffness.
• Click again on the spring to return to main screen. 

5. To change to a different part of the Solar System: 

• Remove all mass from the holder.
• Click on the poster to choose where to do the experiment!

6. Click the Information button to see the controls.

Use this experiment to:

• Test Hooke’s law.
• Measure spring constants.
• Test the ‘limit of proportionality’ for springs.
• Calculate the stored energy of a spring.
• See how different strengths of gravity affect the weight added to a spring.

Download the full Instructions for the Hooke's Law experiment from the link (requires log in)

There are lots of activities to do with the Hooke's Law experiment. You can choose these from one of our Activities, with step-by-step instructions, and record your work on a Worksheet, or use the shorter descriptions in our Questions. Download all of these from from the links (requires log in)

Download the file from the link below to see the full scientific Background to the Hooke's law experiment (requires log in)

There are lots of ways that we use materials that see them change temperature. Some examples include heating systems in buildings (especially storage heaters), simple household appliances such as an iron or an oven, combustion engines in cars, jet engines in aircraft, high speed machines such as drills, and industrial furnaces; however, examples also include applications where the temperature is reduced, for example in refrigerators, freezers and heat sinks, which are used to help cool another component.

A change in a material’s temperature will also result in a change in its heat energy. Different materials, however, will have a different change in heat energy for a given change in temperature.

The materials property we use to show this difference is called specific heat capacity. This property is key to allowing us to understand how components will perform in thermal applications and help us to choose the most appropriate material. If you go to study Physics or Engineering at university you will probably also learn how specific heat capacity values depend on a material’s types of atom, atomic bonding and electrical properties.

Download the attachment to see the one-page quick guide (requires login) 

Download the attached file to see the full instructions for this experiment (requires login)

There are two files to download here, both requiring a login first.

The 'Activities' download gives full step-by-step instructions for four activities with this experiment

The 'Worksheets' download provides worksheets for these four activities that can be printed out and written on directly. 

Download the attached file to see the scientific background to this experiment (requires login)

The FlashyScience Acceleration and Force experiment might use a toy car on a table top but the science you can learn from it helps us to understand the world around us, to design all sorts of new vehicles and machines, and even to understand our bodies better.

At the largest of scales, knowing the huge forces involved with galaxies, stars and planets show us how these huge objects move and even how they form. We use our knowledge of force and acceleration to launch objects into space using rockets and to put satellites into stable orbits. This knowledge also allows us to calculate the acceleration of high performance cars (e.g. F1 cars) and aircraft, to design and build machines with moving parts, and to understand the forces parts of our bodies experience through an area of science called biomechanics. Force and acceleration can even be used to measure the mass of atoms and molecules through scientific techniques called mass spectrometry, and help us to understand how atoms interact in gases.

You can see that knowledge of force and acceleration is essential to lots of areas of science, engineering and our lives in general. Why not try out the FlashyScience Acceleration and Force experiment to learn more for yourself?

Download the quick guide for the Acceleration and Force experiment below (requires login)

Download the full instructions for the Acceleration and Force experiment (requires login).  

The attached activities and associated worksheets are suitable for different levels (needs login to view).

Download the file below to read about the background theory to the Acceleration and Force experiment (requires login). This includes different levels for GCSE Foundation and Higher Levels, and A-level Physics. 

Density is a basic property of materials and liquids. It is important in all sorts of areas of science, engineering and medicine. Density (mass per unit volume) is related to the type of atoms within the material or liquid and how they are arranged. Changing the temperature of a solid or liquid often changes its volume, which also changes its density . Different processing treatments of materials can lock in some of these changes, resulting in materials made of the same atoms but with different densities. Many materials can be ‘porous’ (contain lots of holes) and being able to measure density is a simple way of finding the level of porosity of a material.

The buoyancy of a solid in a liquid depends upon the density of the solid and liquid. Ice floats in liquid water because ice molecules are more widely spaced than those in water, and so the density of ice is lower than that of water.

The density of solids and liquids is also related to a substance’s refractive index and how it interacts with X-rays. For example, your bones are denser than your muscle tissue and so absorb X-rays more; this allows medical images to be created that show the different regions inside your body.

Density is vital to the efficient design of physical objects, particularly for structural and transport applications. There is a huge demand for engineers and materials scientists to create lighter vehicles and aircraft to reduce their power requirements and help reduce our use of fossil fuels.

The FlashyScience Density of Solids & Liquids experiment allows you to develop your scientific and engineering skills in measuring density in three different ways. Why not give it a try?

Download the quick guide for the Density of Solids & Liquids experiment below (requires login)

Download the full instructions for the Density of Solids & Liquids experiment (requires login).  

The attached activities and associated worksheets allow you to use the Density of Solids & Liquids experiment in lots of ways (needs login to view). These activities are for:

1. Regular objects: cube and cuboid
2. Sphere
3. Irregular objects
4. Liquids

Download the file below to read about the background theory to the Density of Solids & Liquids experiment (requires login).

The thermal conductivity of materials is hugely important for how we live today.

Thermally-insulating materials are found in lots of places around the home. This includes safety items such as oven gloves or fire blankets and inside ovens and refrigerators to stop them heating or cooling the rest of your kitchen! Your hot water pipes and water heating system will probably have thermal insulation around them to stop unwanted heat loss. Houses and other buildings usually have thermal insulation around them to reduce heat loss when it is cold outside and reduce heat entering when it is very hot outside. This is important as we try to reduce CO2 emissions from energy use as part of our fight against climate change. Insulating materials are also used around industrial furnaces, in refrigerated vehicles and packages (e.g. for transporting food or medical supplies) in aircraft to keep crew and passengers warm in the cold air, and in spacecraft to stop the insides reaching temperature extremes and protecting the spacecraft itself from burning up if it re-enters Earth’s atmosphere.

Thermally-conducting materials are also very important to heating and cooling systems, such as heating elements in kettles and furnaces, radiators, high speed industrial machines and heat-sinks found in electronic devices.  

Heat conduction is also really important in many renewable energy technologies, such as solar cells (photovoltaics), which work less efficiently if they heat up, and ‘thermoelectric generators’ (TEGs), which are most efficient if they conduct electricity well but conduct temperature weakly.

This huge range of applications means there is a lot of research and development of materials with new thermal conduction properties. How materials conduct heat is also related to their atomic-scale structure – this means that we can learn about the materials from how they conduct heat and change their structure in order to create new properties that are better suited for particular applications. There’s so much to find out! For now, why not start with the FlashyScience Thermal Insulation experiment?

Click below to download the Quick Guide pdf (requires login)

Click below to download the Thermal Insulation Instructions (requires login)

The instructions and worksheets for the following activities can be downloaded using the links below (requires login):

Activity 1: Effect of a material as thermal insulation

Activity 2: Comparison of different materials as thermal insulation

Activity 3: Effect of material thickness on heat conduction

Activity 4: Effect of temperature difference on its rate of change (Advanced Experiment) 

Click below to download the Thermal Insulation Background pdf (requires login)