Chapter 15
Currents
Name the cross-section for current, the endpoints for voltage and the system receiving electrical energy.
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Charge flow and drift
Derive current from a carrier-density model and distinguish net drift from irregular microscopic motion.
Energy per charge
Use a potential reference and distinguish source e.m.f., terminal p.d. and internal energy transfer.
Electrical power and energy
Derive the three power expressions, identify what is held fixed and calculate energy over a stated interval.
Measure input and useful output
Place meters at the chosen load and compare motor-terminal input with useful lifting work over the same events.
Describe an alternating supply
Read signed current and voltage, define period and peak, and use a sinusoid with a stated time origin.
Mean power and rms values
Deduce mean sinusoidal heating power and compare it with an equivalent steady current.
Half-wave rectification
Trace a single-diode circuit in each half-cycle and connect it to the load voltage and current.