#6.1.1a(i)
the action of a transformer: magnetic flux from a coil; induced e.m.f = rate of change of flux linkage
#6.1.1a(ii)
the action of a dynamo: change of flux linked produced by relative motion of flux and conductor
#6.1.1a(iii)
electromagnetic forces; qualitatively as arising from tendency of flux lines to contract or interaction of induced poles; quantitative calculation limited to force on a straight current-carrying wire in a uniform field
#6.1.1a(iv)
simple linked electric and magnetic circuits: flux produced by current turns, need for large conductance and permeance and the effect of increasing the dimensions of an electromagnetic machine; qualitative effect of iron and air gap.
permeance is understood as a magnetic equivalent to electrical conductance and with analogous dependence on the dimensions and nature of the magnetic medium
#6.1.1b
Make appropriate use of:
(i) the terms: B-field, magnetic field, flux, flux linkage, induced e.m.f, eddy currents
by sketching and interpreting:
(ii) graphs of variations of currents, flux and induced e.m.f
(iii) diagrams of lines of flux in magnetic circuits; continuity of lines of flux.
#6.1.1c(i)
\(ϕ = BA \), \(ε = -\dfrac{d(ϕN)}{dt} \)
In the context of Faraday’s and Lenz’s laws
#6.1.1c(ii)
\(F = ILB\)
Calculations restricted to current perpendicular to uniform magnetic field
#6.1.1c(iii)
\(\dfrac{V_1}{V_2} = \dfrac{N_1}{N_2}\) for an ideal transformer
i.e. no energy losses for an ideal transformer
Learners will also be expected to recall the equation relating V and N
#6.1.1c(iv)
\(\dfrac{I_2}{I_1} = \dfrac{N_1}{N_2}\) for an ideal transformer
Learners will also be expected to recall the equation relating I and N
#6.1.1d(i)
observing induced e.m.fs produced under varying conditions such as dropping a magnet through a coil attached to a data logger or oscilloscope
links to 6.1.1a(ii), 6.1.1c(i)
#6.1.1d(ii)
determining the uniform magnetic flux density between the poles of a magnet using a rigid current carrier and digital balance
links to 6.1.1a(iii), c(ii)
#6.1.1d(iii)
investigate transformers
links to 6.1.1a(i), c(iii)(iv)