Hazards, risks and results

In a nutshell

There are many important things to remember when running an experiment. Every experiment and its apparatus has associated health and safety considerations that must be noted. In this lesson, you will learn about health and safety, accurately recording qualitative and quantitative measurements in a table, and using SI units and writing results to appropriate precision.

Definitions

Key Word	Definition
Hazard	A piece of equipment that can pose a risk
Risk	A harmful effect of misusing a piece of equipment
Qualitative	Developing ideas and hypotheses about a subject
Quantitative	Collecting data and physical quantities about a subject

Health and safety

Health and safety is kept in mind throughout the experiment in order to make it as safe as possible to carry out. Some equipment has an associated risk attached to it, and steps must be taken to minimise the risk to the person conducting the experiment.

Example

What is a safety risk associated with working with a laser, and what can be done to minimize it?

Lasers produce a beam of electromagnetic radiation that can be harmful to the skin and eyes.

A good way to minimise the risk is by covering the skin with gloves, and wearing safety glasses.

Even better, make sure the laser is only operating when pointing away from people.

Qualitative and quantitative results

Qualitative results refer to written hypotheses and ideas around the subject, while quantitative results relate to numbers, readings, accuracy and precision. In an experiment, quantitative results must be recorded to a particular standard so that they can be correctly analysed.

The number of decimal places readings are taken to must be chosen and kept consistent based on the method. If the least precise measurement is taken to two decimal places, for example, then all other measurements should be written to two decimal places too, for consistency.

In addition to the actual values, it is extremely important that results are placed in an appropriate table, and tables are drawn correctly. All tables must have, clear headings in columns, and any measurements must have units and are written to a constant amount of decimal places.

Repeat readings

Repeat readings are measurements taken again, using the exact same conditions. If you have multiple readings for a particular set-up, it is good practice to take an average of those readings. Averages are calculated by summing the repeat readings, then dividing by how many readings were taken, so that all repeat readings have an equal influence on the final measurement. Overall, this has the effect of increasing a reading's precision.

Example

$length\,(m)$	$time\,(s)$		$average\ time\,(s)$
$0.82$	$5.4$	$5.2$	$5.3$
$0.96$	$7.6$	$8.0$	$7.8$
$1.20$	$9.9$	$9.7$	$9.8$

The table above has clear headings, with units for appropriate quantities. Time has been split into two columns, representing repeat readings, and an average has been shown in the final column.

All measurements of length are given to two decimal points, even if the last digit is a zero. All measurements of time are given to one decimal place.