Electric fields

Nature of science:

Modelling: Electrical theory demonstrates the scientific thought involved in the development of a microscopic model (behaviour of charge carriers) from macroscopic observation. The historical development and refinement of these scientific ideas when the microscopic properties were unknown and unobservable is testament to the deep thinking shown by the scientists of the time. (1.10)

• Charge
• Electric field
• Coulomb’s law
• Electric current
• Direct current (dc)
• Potential difference

Applications and skills:

• Identifying two forms of charge and the direction of the forces between them
• Solving problems involving electric fields and Coulomb’s law
• Calculating work done in an electric field in both joules and electronvolts
• Identifying sign and nature of charge carriers in a metal
• Identifying drift speed of charge carriers
• Solving problems using the drift speed equation
• Solving problems involving current, potential difference and charge

• Electricity and its benefits have an unparalleled power to transform society

Theory of knowledge:

• Early scientists identified positive charges as the charge carriers in metals; however, the discovery of the electron led to the introduction of “conventional” current direction. Was this a suitable solution to a major shift in thinking? What role do paradigm shifts play in the progression of scientific knowledge?

Utilization:

• Transferring energy from one place to another (see Chemistry option C and Physics topic 11)
• Impact on the environment from electricity generation (see Physics topic 8 and Chemistry option sub-topic C2)
• The comparison between the treatment of electric fields and gravitational fields (see Physics topic 10)

• Students will be expected to apply Coulomb’s law for a range of permittivity values

Data booklet reference:

• Aim 2: electrical theory lies at the heart of much modern science and engineering
• Aim 3: advances in electrical theory have brought immense change to all societies
• Aim 6: experiments could include (but are not limited to): demonstrations showing the effect of an electric field (eg using semolina); simulations involving the placement of one or more point charges and determining the resultant field
• Aim 7: use of computer simulations would enable students to measure microscopic interactions that are typically very difficult in a school laboratory situation