Elenco Snaptricity&reg - Manual (Page 27)

-26-
Educational Corner:
One Way Around Project #17
Connecting parts in series is one way of arranging
them in a circuit. The advantage of it is that wiring
them together is simple. The disadvantage is that if
one lamp breaks, all three will be off.
Snappy says: the 0V or “–”
side of the battery is often
referred to as “ground”,
since in house or building
wiring it is connected to a rod
in the ground as protection
against lightning.
In this circuit the lamps are the resistances
which are limiting the flow of electricity. Placing
resistances in series increases the total
resistance. Advanced users can compute the
total resistance as follows:
R
series
= R1 + R2 + R3 + . . .
The current is the same through all the
resistances in a series circuit. Ohm’s Law says
that Voltage equals Current times Resistance, so
the highest resistances in a series circuit will
have the largest voltage drop across them.
Equal resistances will have the same voltage
drop. In other words:
Voltage (across one resistor) =
Resistance (of that resistor)
Resistance
(total of resistors in the circuit)
x Voltage
(total applied to the series circuit)
Electric Paths
Strings of Christmas lights are
little low-voltage lamps
connected in series to the
house power (120V). They
are inexpensive, but if one
bulb falls out, then the entire
string will be off.
Most strings will still work if
one bulb burns out because a
special heat-activated bypass
wire is built into each bulb.
When the bulb burns out, the
full house voltage is across
the bypass wire, which heats
it until it turns on. Sometimes
only half the bulbs in a string
are lit. This is because some
long strings are actually two
(or more) shorter strings
connected in parallel.
Build the circuit and push the press switch (S2). The lamps
(L4) are all on, but are dim.
Assembly
The three lamps are connected in a series. They are dim
because the voltage from the batteries (B3) is divided
between them.
Description