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Experiment objective:
To understand the
properties of capacitor, and the process of charging
and discharging.
Operation Description:
Connect the two ends of the capacitor to
batteries. Note the polarities: the negative lead of
the electrolytic capacitor should be connected to the
negative terminal of the battery. The capacitor will
then be charged. The voltage of the two ends of the
capacitor (Uc) will keep rising until it reaches to
the same level of the battery's voltage (E). Now Uc=Q
(charging in capacitor)/ C (capacitance of the capacitor).
When the battery is removed and replaced by a resistor
(load), the capacitor will be discharged. The discharging
current (I) = Uc/R. Finally the capacitor will discharge
to its initial state.
The experiment:
Connect the circuit as shown in the diagram
(circuit 4). Then connect the red wire W2 from spring
no. 21 to no. 15. A flash comes out from the LED (D)Repeat
the process if you do not get this result. When the
red wire is connected to spring no. 21, the capacitor
is charging. When it is connected to spring no.15, it
is discharging. If you replace the capacitor with another
one having larger capacitance, and charging amount will
be greater and when discharging the LED will light up
longer and brighter, vice versa.
Functions of electronic components
(Summary):
*Light-emitting
diode (D) as indicator;
*Resistors
(R1and R2) for limiting electric current;
*Battery
(E) as electric supply; and
*Capacitor
(C) for charge and discharge.
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