Essential idea: Electric cells allow us to store energy in a chemical form.
Nature of science:
Long-term risks: Scientists need to balance the research into electric cells that can store energy with greater energy density to provide longer device lifetimes with the long-term risks associated with the disposal of the chemicals involved when batteries are discarded. (4.8)
Understandings:
Cells
Internal resistance
Secondary cells
Terminal potential difference
Electromotive force (emf)
Applications and skills:
Investigating practical electric cells (both primary and secondary)
Describing the discharge characteristic of a simple cell (variation of terminal potential difference with time)
Identifying the direction of current flow required to recharge a cell
Determining internal resistance experimentally
Solving problems involving emf, internal resistance and other electrical quantities
Guidance:
Students should recognize that the terminal potential difference of a typical practical electric cell loses its initial value quickly, has a stable and constant value for most of its lifetime, followed by a rapid decrease to zero as the cell discharges completely
Data booklet reference:
ε=I(R+r)
International-mindedness:
Battery storage is important to society for use in areas such as portable devices, transportation options and back-up power supplies for medical facilities
Theory of knowledge:
Battery storage is seen as useful to society despite the potential environmental issues surrounding their disposal. Should scientists be held morally responsible for the long-term consequences of their inventions and discoveries?
Utilization:
The chemistry of electric cells (see Chemistry sub-topics 9.2 and C.6)
Aims:
Aim 6: experiments could include (but are not limited to): investigation of simple electrolytic cells using various materials for the cathode, anode and electrolyte; software-based investigations of electrical cell design; comparison of the life expectancy of various batteries
Aim 8: although cell technology can supply electricity without direct contribution from national grid systems (and the inherent carbon output issues), safe disposal of batteries and the chemicals they use can introduce land and water pollution problems
Aim 10: improvements in cell technology have been through collaboration with chemists
Comparing internal resistance of a 9-V battery to AAA battery.
Determine Internal Resistance of a Cell.
Important Vocabulary - Quizlet of Topic 5 Vocab
Conservation of Charge
Video Lectures - Passionately Curious
Video Lectures - Andy's Physics Stuff
Khan Academy -Electric current, resistivity, and Ohm's law
EE Circuit Analysis - Much of this goes beyond the scope of HL/SL Physics but it provides a very detailed description of circuit components and theory.
Notes in Slide Format:
Extensive Notes (ppt)