The capacitance is a property of a conducting body or system
that determines the magnitude of the charge that is produced thereby unit
potential. The symbol is C. The unit of capacitance is the farad but it is usually
more convenient to make use of the micro farad.
Any system, possessing appreciable capacitance, in which an
appreciable charge is produced by application of an e.m.f. it the e.m.f. is
continuous, only a momentary rush of current will be produced, but if the
e.m.f. is alternating, a current will surge in and out of the capacitor which
will be in advance of the e.m.f. in phase. Capacitors are therefore used to improve
the power factor of a system. Formerly more usually called condenser or
capacity.
Capacitors are widely used in electronic and electrical
systems. A capacitor stores an electrical charge between two conductors separated
by an insulator. This is similar to a battery. One plate of the capacitor is
positively charged, while the other has a negative charge.
The charge stored in a capacitor is proportional to the
potential difference between the two plates. For a capacitor with charge Q on
the positive plate and Q on the negative plate, the charge is proportional to
the potential.
Capacitance C = charge
(Q)/ voltage (V)
Understanding by experiment: How to
store a charge in a capacitor?
We can
easily understand the capacitor’s storage process with the help of a simple
circuit diagram. This simple experiment exhibits the capacitor’s storage method.
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Required electronics materials:
One LED
Resistor 220
Ω
Resistor 1k Ω
Capacitor (1000 µF)
Battery (9V)
Connecting wire
Wire stripper
Step 1
First place the 220 Ω and 1 K Ω resistors
on the breadboard or soldering on the board. And connect one end of the 220 Ω resistors
to the 1K Ω resistor.
Step 2
Place the 1000 µF capacitor on the
board and connect the positive of the capacitor to the junction of the 220 µF
resistor and 1K Ω resistor.
Step 3
Connect the other end of the 1K Ω
resistor to the anode of the LED and connect the negative of the capacitor to the
cathode of the LED.
Step 4
Then the positive of the battery
should be connected to the other end of the 220 Ω resistors and the negative of
the battery is to be connected to the negative of the capacitor. Now we can see
the LED glow.
After some
time, remove the battery from the circuit and we can see the LED retaining
charge for some time before it is turned off. This is due to the 1000 µF capacitor discharging the charge.
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