Q: Power and capacitors
A:
Capacitors are compact and can be charged easily to store energy
Unlike chemical cells, capacitors cannot store a great deal of energy in a small volume
However, capacitors can release the stored energy very quickly and thus generate a
high output of power
This is exactly what happens in a camera flash
You can store about a joule of electrical energy in a normal capacitor
o And when this is released in a time of 1ms, you get a power output of
about 1kW
Q: A rectifier circuit
A:
Q: Smoothing capacitors
A:
Domestic electricity is supplied as AC
o The direction of the current changes rapidly and repeatedly as the
supply voltage cycles from positive to negative and back
The simple rectifier circuit changes an alternating input voltage to a smooth direct
voltage
The diode allows current in only one direction only
Without the capacitor, the output voltage from the circuit would consist of positive
cycles only
With the capacitor, the output voltage is smoothed out and becomes almost direct
voltage of constant value
The ripple in the output voltage can be kept small by making the time constant of the
circuit much greater than the period of the alternating voltage
A:
Capacitors are compact and can be charged easily to store energy
Unlike chemical cells, capacitors cannot store a great deal of energy in a small volume
However, capacitors can release the stored energy very quickly and thus generate a
high output of power
This is exactly what happens in a camera flash
You can store about a joule of electrical energy in a normal capacitor
o And when this is released in a time of 1ms, you get a power output of
about 1kW
Q: A rectifier circuit
A:
Q: Smoothing capacitors
A:
Domestic electricity is supplied as AC
o The direction of the current changes rapidly and repeatedly as the
supply voltage cycles from positive to negative and back
The simple rectifier circuit changes an alternating input voltage to a smooth direct
voltage
The diode allows current in only one direction only
Without the capacitor, the output voltage from the circuit would consist of positive
cycles only
With the capacitor, the output voltage is smoothed out and becomes almost direct
voltage of constant value
The ripple in the output voltage can be kept small by making the time constant of the
circuit much greater than the period of the alternating voltage
