New trends in physics teaching, v.4; The ... - unesdoc - Unesco

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Amount of heat generated relates to the electric current, resistance and time.
Electric power.
Direct current and alternating current.
(3) Electric currents and electrons:
Vacuum discharge.
Cathode rays consist of streams of negatively charged particles.
Electric currents in metals; electrons.
(111) Motion and energy . . . . . . . . . . ninth grade
Objectives: Understanding simple motion of bodies and the work done by light, heat and
electric currents, and developing the elementary concept of energy transformation.
(1) Motion:
Speed and direction.
Frames of reference.
Uniform motion in a straight line.
Distance, speed and time.
Free fall, acceleration of gravity.
(2) Work:
Definition of work.
Work done against friction.
Principle of work.
Power.
(3) Work done by light and heat:
Light can do work.
Heat can do work, work generates heat.
(4) Electric currents and work:
Electric currents produce magnetic fields.
Magnetic field exerts force upon electric currents.
Electric currents can do work.
Work can generate electric currents.
(5) Energy:
Energy is measured by the work which can be done externally.
Gravitational potential energy depends on height and mass.
Kinetic energy depends on speed and mass; qualitative treatment.
Transformations between potential energy and kinetic energy.
Effective utilization of natural resources and energy.
It is true to say that the strategy of the teaching of energy in lower secondary science has been
much more improved by these changes. The reasons are that (1) children in the lower grades have
experienced a range of phenomena which helps them to appreciate the idea of energy; (2) the term
‘work’ has not been used as a name for a type of energy itself, nor has it been used as a rough
name for mechanical energy; (3) the idea that ‘energy is measured by the work which can be
done externally’ is an appropriate treatment for an introductory course, though not complete;
(4) it is enough for the lower stages that various forms of energy are introduced, and that the
convertibility of energy from one form to another is discussed; and (5) it is proper not to touch
on energy conservation, because it needs quantitative treatment.
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