Measurement is the starting point of meaningful scientific understanding. Micrometers are common pieces of equipment used across science and engineering that allow object dimensions to be measured with a high degree of accuracy and precision. This can be vital for designing mechanical components or for experiments in which sample dimensions affect the outcomes, e.g. resistance or stress.

The following quick instructions are also in the downloadable file below:

1. Click on the rotating thumbscrew and drag up or down to open or close the micrometer, the further you move with your mouse the faster it will rotate.
2. Open the micrometer and drag a sample into the gap between the spindle and anvil. The sample will snap into place.
3. Close the micrometer around the sample with the rotating thumbscrew.
4. Read width from the micrometer scale (see below for how to do this).
5. Type width into the appropriate text box and click ‘Check’ to see if you were right (green = correct, red = incorrect).
6. Drag a sample out of the jaws (or press ‘Reset’) to return it to its original 
place and select a new sample.

You can also click ‘New’ for a fresh set of samples with different widths.

To read the micrometer scale (see full instructions for more details):

• Find the largest valued tick mark on the main scale that is revealed from behind the rotating thumbscrew. This gives a whole number of millimetres for sample width. 
• Locate the tick mark on the rotating scale that is most closely aligned with the main scale axis. This gives the number of tenths of a millimetre in the sample width.
• Add the values from the above steps to find the overall sample width.

Download the file below to view the full instructions for the Micrometer experiment.

1. Measure the diameter of ten ball bearing samples. Check to see how many you measure correctly and give yourself a mark out of ten. Repeat this until you get 10/10 every time! 
2. Error analysis:
   1. Measure and record the diameter of ten or more ball bearing samples. 
   2. Use the width data to calculate the volume of each sphere. 
   3. Determine the absolute uncertainty and percentage uncertainty for each diameter measurement. 
   4. Determine the absolute uncertainty and percentage uncertainty for each volume value. 
3. Statistical analysis:
   1. Measure and record the diameter of ten or more ball bearing samples. 
   2. Calculate the mean and standard deviation of the diameter measurements. 
   3. (Advanced experiment) Calculate the standard error of the diameter measurements and from this determine the confidence level of the mean.

Measurement is the starting point of meaningful scientific understanding. Callipers are common pieces of equipment used across science and engineering that allow object dimensions to be measured with a high degree of accuracy and precision. This can be vital for designing mechanical components or for experiments in which sample dimensions affect the outcomes, e.g. resistance or stress.

The following quick instructions are also in the downloadable file below:

1. Drag moveable part of lower jaw to make jaw separation larger than sample width. 
2. Drag sample into lower jaws. Sample will snap into place.
3. Drag moveable jaw blade to close jaws around sample.
4. Read width from scale (see below for how to do this).
5. Type width into ‘Sample Width’ text box and click ‘Check’ to see if you were right (green = correct, red = incorrect).
6. Drag a sample out of the jaws (or press ‘Reset’) to return it to its original place and select a new sample.
7. Click ‘New’ for a new set of samples with different widths.

To read the caliper scale (see full instructions for more details):

• Find the tick mark on the main scale (upper scale) that is just below the ‘zero’mark on the Vernier scale (lower scale). This gives a whole number of millimetres for sample width.
• Locate the tick mark on the Vernier scale that is most closely aligned with any tick mark on the main scale. This gives the number of tenths of a millimetre in the sample width.
• Add the values from the above steps to find the overall sample width.

Download the file below to view the full instructions for the Callipers experiment.

1. Measure the width of ten samples. Check to see how many you measure correctly and give yourself a mark out of ten. Repeat this until you get 10/10 every time! 
2. Error analysis:
   1. Measure and record the width of ten or more samples. 
   2. Use the width data to calculate the cross-sectional area of each sample. 
   3. Determine the absolute uncertainty and percentage uncertainty for each width measurement. 
   4. Determine the absolute uncertainty and percentage uncertainty for each cross-sectional area value. 

3. Statistical analysis:

   1. Measure and record the width of ten or more samples. 
   2. Calculate the mean and standard deviation of the width measurements. 
   3. (Advanced experiment) Calculate the standard error of the width measurements and from this determine the confidence level of the mean.

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.

Electricity powers the modern world. It is essential for electronic devices, home appliances, travel and school, work and leisure.

The widespread use of electricity is because we can make so many components that have different electrical behaviours, and then combine them to make all sorts of devices and machines. These behaviours can be seen most easily by creating a graph of the electrical current (I) through a component against the potential difference (V) placed across it. This graph is known as a component’s IV characteristic.

The simplest component is the electrical resistor. These have fixed electrical resistance, which means the electrical current is proportional to the potential difference and the IV characteristic is linear. Resistors are vital to almost all electrical devices, from a mobile phone to the world’s most powerful supercomputer, a flashlight to electric vehicles, an electric toothbrush to a medical scanner, your internet router to a communications satellite, or a vacuum cleaner to air-conditioning.

Diodes are made of two different semiconductor materials joined together and only allow electricity to flow in one direcion through them. They are hugely important in electronics and electrical engineering. They are most often used to convert alternating current (AC) electricity to direct current (DC), for example to convert mains electricity into 12 V DC used for charging mobile devices. They are also widely used to protect electronic circuits by preventing unwanted currents. 

Filament lamps might not be used for lighting as much as they once were but they show interesting electrical effects. They contain a long, thin metal 'filament' that heats up when high electrical current is flowing, which results in it starting to glow and give off light. The heating also changes the filament's electrical resistance, which results in a non-linear IV characteristic.

This virtual experiment will allow you to explore the electrical behaviour of resistors, diodes and filament lamps. You can take measurements of current and potential difference, plot a graph of their IV characteristics, and find their resistance values.

Download the file from the link below to see the Quick Guide to use the IV Characteristics of Devices experiment (requires log in)

Download the file from the link below to see the full Instructions for the IV Characteristics of Devices experiment (requires log in)

The activity sheets can be downloaded using the link below (requires log in). This contains details of the following:

• ACTIVITY 1: IV characteristics of resistors
• ACTIVITY 2: IV characteristic of a filament lamp
• ACTIVITY 3: IV characteristic of a diode
• ACTIVITY 4: Electrical power use in resistors
• ACTIVITY 5: Electrical power use in filament lamps

Download the file from the link below to see the scientific Background to the IV Characteristics of Devices experiment (requires log in)

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. Download the Questions from the link (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)