A2 Physics Alternating Currents

what is period in terms of AC

time taken for one complete cycle of an alternating current

what is frequency in terms of AC

number of complete cycles per unit time

what is peak value in AC

the amplitude of the oscillating current or voltage

formula for representing a sinusoidally alternating current or voltage

what is mean power in a resistive load half of

it is half of the maximum power for a sinusoidal alternating current

what is the difference between root mean squared and peak values

• root mean squared would give the equivalent DC value that would give the same power dissipation

• peak values is maximum amplitude of the wave

formula for root mean squared

what is half-wave and full-wave rectification

• rectification is converting an AC to DC

• half-wave consists of the positive half-cycles

• full-wave reverses the polarity the negative half-cycles to make it more efficient

what is the use of a single diode for the half-wave rectification

only allows movement only in one direction

what is the use of four diodes (bridge rectifier) for the full-wave rectification

• diodes switch on and off to allow current to flow from one end to another

• In the diagram below, when P is positive, diodes 1 and 2 on opposite sides will conduct. When Q is positive, diodes 3 and 4 will conduct. Thus the resistor will always have its upper terminal positive and its lower terminal negative

what is smoothing

reduction in the variation of the output voltage or current using capacitors

what does the capacitor do in smoothing

• placed parallel to resistor

• capacitor charges up input voltage and discharges gradually when voltage drops

how does a graph of smoothing look like