The capacitor charges when voltage moves from Vrms to Vpeak. It discharges when voltage moves from Vpeak to Vrms.
Frequency of Vrectified reaching its peak value = 2 x Frequency of Vinput.
root mean square value of alternating current = direct current that delivers same average power as alternating current to a resistive load.
In alternating current electrons flow forward and backward. Some electronic devices require direct current.
Q. Explain why heating occurs when there is an alternating current in a resistor.
Heating effect is independent of current direction. Voltage and the current are always in phase in a resistor. P = VI is always positive.
Q. Suggest why high voltages are used.
For same power transmission, higher voltage means lower current. Lower current means less power loss in transmission cables.
Q. Suggest why the voltage is alternating.
Generators produce alternating current. Transformers only work with alternating current. Voltage can be easily stepped up or down.
Q. Explain what happens to the air surrounding the crystal.
Alternating voltage causes the piezoelectric crystal to vibrate. The vibrations of the crystal induce vibrations in the air. The frequency is 50,000 Hz, placing these vibrations in the ultrasound range. This process also generates an electromotive force across the other crystal.
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