Measurements 

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.

Use this experiment to find out more!

Download the file below for the quick guide for the Micrometer experiment or follow these brief instructions:

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 for 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.

Use this experiment to find out more!

Download the file below for the quick guide for the Callipers experiment or follow these brief instructions:

1. Drag the moveable part of the lower jaw to make jaw separation larger than the sample width.
2. Drag the sample into the lower jaws. Sample will snap into place.
3. Drag the moveable jaw blade to close the jaws around the sample.
4. Read the width from the scale (see below for how to do this).
5. Open the jaws and drag the sample out to return it to its original place and select a new sample.

To read the calliper 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 for 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.

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 contain 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!

Use this experiment to find out more!

Download the file below for the quick guide for the Ohm's Law experiment (requires login) or follow these brief 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.

​Download the file below for full instructions for the Ohm's Law experiment (requires log in).

Download the files below for activities for the Ohm's Law experiment (requires login).

• ACTIVITY 1: Investigate what the different coloured bands on resistors mean
• ACTIVITY 2: Learn how to use a DMM to measure electrical resistance
• ACTIVITY 3: Explore the effect of the tolerance band (band 4) on resistors
• ACTIVITY 4: Explore the statistics of resistance values from resistors with the same band colour coding
• ACTIVITY 5: Investigate Ohm’s law by measurement of voltage and current with a resistor
• ACTIVITY 6: Investigate Ohm’s law by measurement of current for different resistors with a fixed voltage
• ACTIVITY 7: Investigate Ohm’s law by measurement of voltage for different resistors with a constant current
• ACTIVITY 8: Investigate the power consumption due to electricity flowing in a single resistor
• ACTIVITY 9: Investigate the power consumption due to electricity flowing through different resistances

(Available as separate downloads or all activities)

*NEW* Now also available in editable Microsoft Word format

Download the file below for the background science behind the Ohm's Law experiment (requires log in).