In the construction of an efficient mains transformer, the core is made of laminated soft iron and the coils (windings) are made of copper. Which of the following statements best explains the choice of these materials to minimize energy loss?
Soft iron is easily magnetized and demagnetized to reduce hysteresis loss, and copper has very low electrical resistivity to minimize thermal losses in the windings.
Soft iron is a hard magnetic material that maintains a permanent magnetic field, and copper has high tensile strength to prevent coil deformation.
Soft iron has a high electrical resistance to prevent any magnetic flux from escaping, and copper has high magnetic permeability to guide the fields.
Soft iron has extremely high electrical conductivity to encourage eddy currents, and copper has a high thermal capacity to absorb heat.
275 exam-style questions on CIE IGCSE Physics 4.5 Electromagnetic effects, covering 4.5.1a Electromagnetic induction, 4.5.1b Direction of an induced e.m.f., 4.5.2 The a.c. generator, 4.5.3a Magnetic effect of a current and its applications, 4.5.3b Strength and direction of the field around wires and solenoids, 4.5.4a Force on a current-carrying conductor, 4.5.4b Force on beams of charged particles, 4.5.5 The d.c. motor, 4.5.6a Construction and operation of a transformer, 4.5.6b Turns ratio and current in a transformer, and 4.5.6c High-voltage transmission of electricity. Each one has a worked solution and a mark scheme showing where the marks go.