Physics Demonstrations at Cal Poly Pomona
Demo Index:
Pira Index:
Title:
SERIES AND PARALLEL CIRCUITS
Description:
Demonstrates series and parallel circuits with light bulbs.
Equipment:
1. Light bulb apparatus A, B, C (below)
2. Variac
3. Light bulbs (usually in sockets of #1))
4, Glove--heavy cloth type
•Show that bulbs in series all go out if one is removed, but not so with the bulbs in parallel.
•Change the # of bulbs in the circuit--with more bulbs in series they glow more dimly. With more bulbs in parallel they glow brightly.
•Figure C arrangement shows that high wattage bulbs conduct more current.
Procedure:
1. Plug circuit as in figure A, B, or C into variac.
2. Loosen bulbs as desired to demonstrate effects of each circuit.
3. Figure C circuit is more complex. Unscrew the center three bulbs in any combination and watch the brightness change each time.
Warning: Do not touch metal surfaces when circuit is turned on.
If they specify only series and parallel they do not want fig. C type with various size bulbs.
