Elenco Snaptricity&reg - Manual (Page 28)

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Educational Corner:
Many Paths Project #18
Connecting parts in parallel is another way of arranging them in a circuit. The advantage of it is
that if one burns out, the others will still work (unscrew one of the bulbs to prove this). The
disadvantage is that wiring the parts together is more complex than with series circuits.
All large circuits are made of combinations of series and parallel circuits.
Snappy says: most
of the lights in your
house are connected
in parallel; so if one
bulb burns out then
the others are not
affected.
In this circuit the lamps are the resistances which are
limiting the flow of electricity. Placing resistances in
parallel decreases the total resistance. Advanced
users can compute the total resistance as follows:
The voltage is the same across all the resistances in a parallel circuit. Ohm’s Law says that
Voltage equals Current times Resistance, so the lowest resistances in a parallel circuit will
have the most current through them. Equal resistances will have the same current. In other
words:
Current (through one branch) =
Resistance
(total in all OTHER parallel branches)
Resistance
(total of resistors in all branches)
x Current
(total applied to the parallel circuit)
Electric Paths
Build the circuit and push the press switch (S2). The lamps
(L4) are all bright.
Assembly
The three lamps are connected in parallel with one another.
They are bright because each lamp gets the full battery
voltage. The voltage pushes the current with equal force,
because all are 4.5V, down each path.
Description
1 1 1 1
= + + + . . . .
R parallel R1 R2 R3