Part A - Concepts
A.1 Energy and particles
A.1.1 What are Fields?
Essential Idea:
The concept of fields was developed to help explain the “action at a distance” observed in the motion of masses, charges and magnetic materials in the presence of each other.
Understanding the Nature of Science:
Fields are a convenient concept for the quantitative interpretation of the phenomena of how forces can act over a distance.
Visualizations of fields are helpful to our understanding of a range of phenomena.
Electromagnetic radiation is understood as the interaction of electric and magnetic fields.
Moving within fields may involve transfer of energy and work being done.
Guidance:
Electric fields are associated with charged particles and changing magnetic fields.
Magnetic fields are associated with permanent magnets, moving charges and a changing electric field.
Gravitational fields are associated with masses.
An understanding of what fields represent is required and not the reproduction of different field patterns.
A.1.2 What is Energy?
Essential Idea:
Often in science abstract concepts are useful and the concept of “energy” has been developed to help explain observations and measurements of causally linked phenomena.
Understanding the Nature of Science:
Energy has intrigued scientists from the earliest times. It is a concept common to all sciences.
Energy is the ability to do work. Work done equates to the energy transferred.
Energy is a concept that is best understood by exploring the underlying mechanisms (both microscopic and macroscopic) in a process.
In developing the concept of energy, models have been built up to help explain the different ways in which energy exists.
Einstein’s equation E=mc2 shows that mass and energy are interchangeable. This applies to all energy transfers.
Guidance:
The understanding of energy should focus on the underlying mechanisms and not on descriptions in terms of energy changes.
A.1.3 Newton’s Laws of Motion
Essential Idea:
Newton was able to explain motion through developing a set of laws that can be expressed mathematically. The laws are obeyed by all objects, regardless of the nature of the force or the situation of the objects. Through his laws, Newton was able to create an explanation of motion that clarified thinking, explained observations, and made successful predictions.
Understanding the Nature of Science:
Newton’s laws are independent of the types of force experienced by the object.
Newton’s second law can be expressed mathematically as F=ma, where acceleration is a vector quantity that has the same direction as the force that caused it.
Newton’s laws can make predications about the motion of objects.
Circular motion involves a force acting towards the centre of rotation.
Guidance:
Calculating acceleration using F=ma and a = Δv/t required.
A.1.4 Fundamental particles
Essential Idea:
Various models have been proposed to explain the underlying structure of the material universe. Particle models supported by evidence that match our observations provide useful unifying concepts and enable accurate predictions to be made.
Understanding the Nature of Science:
Over time humans have postulated a variety of models to explain the structure of matter.
Some models were based on speculation and logic (e.g. early Greek theories of the four “elements”: fire, earth, air and water).
Later models were based on experimental findings and the need to explain these.
Dalton and other chemists in the 19th century interpreted the world in terms of atoms, molecules and ions.
Substances with different numbers of protons in their atoms are called elements. There are only 98 long lasting elements in the universe.
Mendeleev was able to produce a periodic table of the elements when he observed patterns in their behaviour and properties and was able to predict the existence of missing elements that were subsequently discovered.
In the 20th century the work of Thompson, Millikan, Rutherford and Chadwick led to an understanding of the structure of atoms and the existence of subatomic particles.
More recently large multinational teams of scientists working in high budget, research centres, such as CERN, have produced evidence that these subatomic particles are in turn comprised of fundamental particles and at a deeper level even more basic units such as quarks.
Guidance:
A qualitative, descriptive understanding is sufficient.
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