Data Sheet

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109. Electricity Storage

Build the circuit shown on the left, then connect points A and B with the

spring wire (9). The heart LED (69) will turn on and then fade out as the

470mF capacitor (74) is charging.

Now remove the spring wire (9) from points A and B and connect the

spring wire (9) between points B and C. The lamp (76) will turn on for a

while and then fade out. This is because when the 470mF capacitor (74)

is charged, it stores electrical energy. While this electrical energy is

being discharged through the Base of the NPN transistor (50), current

is enabled to ow from Collector to Emitter lighting up the lamp. Once

all the electrical energy is discharged from the 470mF capacitor (74),

current no longer ows through the Base, and thus current will no

longer ow from the Collector to the Emitter and the lamp (76) turns

off.

110. Capacitor Discharge

Build the circuit shown on the left, connect points A and B with the

spring wire (9), then turn on the switch (62). The heart LED (69) will

light and then fade out as the 470mF capacitor (74) is charging.

Remove the spring wire (9) from points A and B and place the spring

wire (9) across points B and C. You will see the ber tree (40) light for a

while and fade to be very dim as the 470mF capacitor (74) discharges.

Notice in this case, though, that the colorful LED (72) will stay dim for a

long time. This is because it takes a long time for the 470mF capacitor

(74) to fully discharge, and even a small current through the colorful

LED (72) is enough to light it dimly.

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