Substituting the assumed form of the electric field (Equation 7.20) into the empty-space version of Gauss's law (Equation 7.16) gives

The first two partial derivatives are equal to zero because f does not depend on x or y. So we obtain

Author(s): The Open University

A great deal of attention, by governments and the media, is focused on the environmental threat posed by carbon dioxide (CO2) emissions and on the urgent need to reduce them. Mainly due to the burning of fossil fuels, the level of CO2 in the atmosphere has increased by some 36% since pre-industrial times. According to recent estimates (IPCC, 2007), this increase has contributed more than 50% of the global warming attributed to human activities. The rest is due to enhance
Author(s): The Open University

Information is everywhere these days â€“ in the form of images, written records, tables and graphs. In this part of the unit we want you to realise how useful graphs can be to analyse numerical information, and to show you some techniques that can help you decide how reliable this numerical information is.

It's often difficult to spot a trend or a relationship in a long list of numbers. Because the human mind is highly adapted to recognising visual patterns, it is often much easier to u
Author(s): The Open University

A common healthcare example that uses addition and subtraction involves calculating the fluid balance of a patient.

Fluid balance is a simple but very useful way to estimate whether a patient is either becoming dehydrated or overfilled with liquids. It is calculated, on a daily basis, by adding up the total volume of liquid that has gone into their body (drinks, oral liquid medicines, intravenous drips, transfusions), then adding up the total volume of liquid that has come out of their
Author(s): The Open University

Figure 2 shows a picture of a ruler. The major units are marked in centimetres (1 to 11 cm), whilst the intervals between the centimetres have each been split into ten equal, smaller units. These minor units are therefore tenths of a centimetre, commonly known as â€˜millimetresâ€™. (There are 10 millimetres in 1 centimetre
Author(s): The Open University

Simple rules for dealing with orders of magnitude and decimal points in decimal numbers: values ten times bigger than the order of magnitude you are looking at go to the left, ten times smaller go to the right, and less than 1 to the right of the decimal point.

Note: in many European countries, a comma is used instead of a decimal point. For instance in France and Germany two and a half (in other words 2.5) can be written as 2,5. This is important to bear in mind, for example, if
Author(s): The Open University

Suppose you have less than one of any particular unit: how would you represent that using the decimal system?

Well, we've already seen that decimal numbers rely on a positional system, in which values get smaller by factors of ten as you read from left to right. If we continue doing this, then the number to the right of a single unit represents tenths of that unit. A decimal point is then used to mark the boundary between the whole units and tenths of that unit.

For instanc
Author(s): The Open University

Many different systems for writing numbers have been developed over the history of humankind.

The easiest way of counting small numbers is to use your fingers, and for this reason many numerical systems, such as the decimal system, are based around the number ten. But what happens when you run out of fingers to count on?

Numbering systems get round this problem by using a system of scale in which many small units are represented by a single larger unit, and many of these la
Author(s): The Open University

By the end of this unit you should be able to:

• understand the decimal system of numbering (hundreds, tens, units);

• explain the best way to write down decimal numbers and associated units of measurement in the healthcare workplace, in a manner that avoids confusion;

• understand the concepts of discrete and continuous variables and the best types of graphs used to represent these data;

• analyse, construct and extract information from grap
Author(s): The Open University

This sample of S110 material is taken from Module 2, entitled Using numbers and handling data. As you read the material, bear in mind that it is taken from a work-based course, designed for those who are employed in the health services, perhaps as a paramedic or as operating theatre staff. If you were a student on the course, you would have an OU tutor to help you, plus a work-based mentor supplied by the employer â€“ normally the NHS. The aim is to use the workplace as a teaching aren
Author(s): The Open University

The content acknowledged below is Proprietary (see terms and conditions). This content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Licence

Grateful acknowledgement is made to the following sources for permission to reproduce material in this unit:

## Author(s): The Open UniversityLicense informationRelated contentExcept for third party materials and/or otherwise stated (see terms and conditions) the content in OpenLearn is released for use under the terms of the Creative Commons Attribution-NonCommercial-Share

Now you have completed this unit, try the following questions to test your understanding of this material.

## Question 19

Geological time can be divided into a number of Eons, Eras and Periods, with further subdivisions into sub-Periods or series and epochs. These are arranged chronologically, with the oldest at the bottom, younging upwards to form the stratigraphic column (Figure 2).

The stratigraphic column can be looked at in
Author(s): The Open University

The size of a water droplet may seem very small but in terms of the scale of scientific measurement it is relatively large. You already know that water is made up of molecules so now consider a water droplet more closely to see what water molecules are made up of. If you could magnify a water droplet until it no longer has a smooth surface, you would see something similar to that shown in Author(s): The Open University

Most of the usable water is derived from the 1.1 Ã— 105 km3 that falls over the land surface each year as rain, snow, sleet or hail. The collective term for all of these sources of water is precipitation. At this point, you will consider the size of the drops of water that make up clouds or rain (Figure 5).

Author(s): The Open University

Brain imaging and aphasic studies helped us localise the subparts of language processing within the brain. However, they have shed little light on how processing unfolds in real time. This is because contemporary brain imaging is quite poor at showing changes in activity through time in fine detail, so it is hard to pick up something that may be happening slightly before something else.

By the end of this unit you should be able to:

• recognise definitions and applications of each of the terms printed in bold in the text;

• understand and apply basic grammatical terminology;

• describe briefly the different types of sounds used in speech in both acoustic and articulatory terms;

• outline the key features of human language as compared to the vocalisations of other species;

• describe the complex psychologi
Author(s): The Open University

The document attached below includes the seventh section of Mountain building in Scotland. In this section, you will find the following subsections:

• 7.1 Introduction

• 7.2 Mid-Ordovician to Silurian sedimentation in the Midland Valley Terrane

• 7.2.1 Ordivician sedimentation

• 7.2.2 Silurian sedimentiation

• 7.2.3 Summary of Section 7.2

• 7
Author(s): The Open University

The average distance between human ears is about 20 cm. Therefore, if a sudden noise comes at you from the right, perpendicular to your head, it will reach your right ear 0.6 ms before it reaches your left ear. For a sound coming from directly in front of you there will be no delay, and at angles between, the delay will be between 0 and 0.6 ms. Therefore there is a simple relationship between the location of the sound source and the interaural delay. It is this delay that enables us to locali
Author(s): The Open University

Some findings indicate that, for moderate loudness levels, humans can detect a frequency change of about 1 to 3 Hz for frequencies up to about 1000 Hz. Figure 37 shows a plot of the smallest frequency difference for which two tones can be discriminated for a number of reference tones. You can see from the figure that up to about 1000 Hz, the D
Author(s): The Open University