Electric and gravitational fields

This list covers a topic that is usually taught in upper 6th physics lessons.

It is useful if students can recognise that fields are part of the model to explain forces acting at a distance and that they recognise how diagrams are used to represent the strength of these fields. Students will have some qualitative ideas about gravitational and electric fields from GCSE, when they meet the idea of gravity and electrostatics. However, they may not have met the idea of the field lines in relation to these two fields or the quantitative relationships.

It is possible to demonstrate electric fields using a variety of demonstrations, some of which are described in the items in this list.

The list also contains items which have problems that students can answer, tutorial videos that can be found on youtube and simulations that can be used to explore the quantitative relationships in electric and gravitational fields.

Learning opportunities included within this list cover:

force fields, concept and definition
gravitational force and inverse square field for point (or spherical) masses
electric force and field for point (or spherical) charges in a vacuum
electric and gravitational potential and changes in potential energy
uniform electric field
similarities and differences between electric and gravitational fields

Whilst this list provides a source of information and ideas for experimental work, it is important to note that recommendations can date very quickly. Do NOT follow suggestions which conflict with current advice from CLEAPSS or recent safety guides. eLibrary users are responsible for ensuring that any activity, including practical work, which they carry out is consistent with current regulations related to Health and Safety and that they carry an appropriate risk assessment. Further information is provided in our Health and Safety guidance.

Quality AssuredCategory:SciencePublisher:Institute of Physics

This resource links to four complete lessons, plans, experiments and resources on the topic of electric fields. Following the link to the lessons it is possible to use the lesson as described or gain ideas for practical activities and problems (with solutions) for use in lessons designed in school. The episodes in this topic are:

Episode 406: Fields, field lines and equipotentials

Episode 407: Coulomb’s law

Episode 408: Field strength, potential energy and potential

Episode 409: Uniform electric fields

This resource is particularly useful for those composing schemes of work or those with less experience teaching A level physics. It is also useful for those looking for alternative ideas to incorporate into their lessons.

This simulation allows students to move point charges around the ‘playing field’ and see how they interact. It is possible to place two point charges at the same position to increase and decrease the size of the charge. The arrows show the direction of the field and their faintness describes the strength. This can be used for qualitative descriptions, however there is a tape measure function and the ability to measure potentials using ‘e-field sensors’. From it students can be asked to make predictions and describe the strength and direction of electric fields. This Youtube video gives an idea of how Paul Anderson uses this PhET simulation to show how adding charges increases the strength of the electric field.

Quality AssuredCategory:SciencePublisher:National STEM Learning Centre and Network

Using a Van de Graaff generator it is possible to produce very dramatic demonstrations that convey important aspects of topics related to electric fields and currents.

This video is aimed at teachers and gives practical advice on how to use a Van de Graaff generator. This piece of equipment can perform inconsistently in different conditions, but the video gives advice on how to combat these issues.

On this page from the Practical Physics website there are links to several practical activities that demonstrate how force fields can provide an explanation of how forces can act at a distance. A high voltage supply will be required for these experiments. The resources contain diagrams on how to set up the experiments, with step-by-step instructions and some teaching notes.

This link goes to the contents page for the 16-19 electrostatics section of the School Physics website. The site is useful for students who would find concise notes with clear diagrams useful. Students will need to be directed to the relevant pages, as there are links to topics such as capacitors on the page too. However, the resource is comprehensive, covering:

Coloumb's Law, Electric fields, Forces between two charged plates, Equipotentials, and Electric potentials.

The pages link to worksheets with a good number of problems (usually without solutions unfortunately). However, this page contains questions with worked answers: Electric field problems.

This has a worked example comparing the electric force and gravitational forces in a hydrogen atoms. A useful resource for drawing together the aspects of the two fields topics.

Quality AssuredCategory:SciencePublisher:Institute of Physics

Although the link is only to the ‘introduction’ section of the resource, there are links from there to the independent lessons. The resource is useful for those compiling a scheme of work, those with little experience of teaching A level physics or those experienced teachers looking for alternative activities. The teaching notes for the lessons contain suggested practical activities and explanations, as well as problems with worked solutions.

The linked page outlines the learning opportunities in this series of lessons.

The learning episodes in this series are:

Episode 401: Newton’s law of universal gravitation

Episode 402: Fields, field lines and field strength

Episode 403: Orbital motion

Episode 404: Gravitational potential energy and gravitational potential

In this video Paul Andersen explains how the gravitational field strength is directly related to the mass of the object and indirectly related to the square of the distance from the center of mass. It then goes on to explain why the surface of the Earth does not have the same value for the gravitational field strength at every point.

From this School Physics contents page it is possible to navigate to many different pages containing concise notes, with diagrams explaining a large range of concepts related to A level physics gravitational fields topics.

For example, the relationship between G and g, Newton's Law of Gravitation, and Gravitational Potential.

The resource is useful for students to check their understanding against and the images may be useful for teachers to project to help make their explanations clear. The resource also contains questions that students can answer, although unfortunately without answers, which can be purchased separately.

From the website S-Cool these revision notes will be a useful reference to students. The webpage use a table format to compare the properties of gravitational and electrical fields.

Quality AssuredCategory:SciencePublisher:John Murray

This is an old resource, which is a PDF copy of an older book. Although the resource may not be found to be suitable to use as it is (it references BBC programs from the 1960's and Scientific American articles from the 1970's) there are many positive attributes for teachers compiling lessons and schemes of learning. For example on page 5 there is an extension activity about the determination of G. On page 11 there is an experiment on measuring the force between two charged particles that could be tried. The book also intergrates the topics of electric and gravitational fields in a way not many modern textbooks do, and makes links between physics concepts and calculus that may be of interest to students studying mathematics alongside their A level in physics. The resource also contains 'developmental questions', which are more thought provoking. Throughout the resource there is a large volume of questions to keep students thinking.