### Marilynn Stone This SMART website is hosted by the Illinois Institute of Technology

This lab is designed to help students learn the differences between series and parallel circuits and to actually connect bulbs in series and parallel.

To connect the bulbs in series, there will be only one path from the positive terminal of the battery, through each bulb then back to the negative terminal of the battery.

To connect the bulbs in parallel, each bulb must have a complete path from the positive terminal of the battery to the negative terminal of the battery.

Information: a.  A series circuit contains only one path for the current.

b.  A parallel circuit has more than one path for the current.

c.  The circuit consists of three bulbs and five switches.  Note that switch 5 can be open, or closed left or right.

d.  All of the other switches can either be open or closed.

If you want to print this out, it is best to copy it into a word processor and set up the pages.

Note that the circuit just consists of knife switches and flashlight bulbs connected with bell wire.

(Hint:  If you use a low voltage D.C. power supply, connect all three bulbs in series and turn up the voltage until you can see that the bulbs are lit.  If the voltage is too high, when only one bulb is connected, it will probably burn out.)

This is a picture of the actual circuit board which the students use to check their circuits.

Purpose:  To connect the bulbs in various series and parallel circuit combinations.

Procedure: 1.  For each of the ten problems, state whether each of the five switches is open or closed. (Remember that

switch 5 can be open or closed either left or right.)

2.  Test your results on the circuit board to see if the bulbs light correctly.

(In series, if you unscrew one of the bulbs, the others will go out also.  In parallel, only the bulb that you unscrew will go out.)

Problems:

 1.  Connect B1 in series 6.  Connect B2 in series S1 = S4 = S1 = S4 = S2 = S5 = S2 = S5 = S3 = S3 =

 2.  Connect B2 and B3 in series 7.  Connect B3 in series S1 = S4 = S1 = S4 = S2 = S5 = S2 = S5 = S3 = S3 =

 3.  Connect B1, B2, B3 in series 8.  Connect B1and B3 in series S1 = S4 = S1 = S4 = S2 = S5 = S2 = S5 = S3 = S3 =

 4.  Connect B1and B2 in parallel 9.  Connect B1 and B3 in parallel S1 = S4 = S1 = S4 = S2 = S5 = S2 = S5 = S3 = S3 =

 5.  Connect B1, B2, B3 in parallel 10.  Connect B1 and B2 in series S1 = S4 = S1 = S4 = S2 = S5 = S2 = S5 = S3 = S3 =

 1.  Connect B1 in series 6.  Connect B2 in series S1 =  Closed S4 =  Open S1 =  Open S4 =  Closed S2 =  Open S5 =  Closed right S2 =  Closed S5 =  Closed right S3 =  Open S3 =  Open

 2.  Connect B2 and B3 in series 7.  Connect B3 in series S1 =  Open S4 =  Closed S1 =  Open S4 =  Open S2 =  Closed S5 =  Closed left S2 =  Closed S5 =  Open S3 =  Open S3 =  Closed

 3.  Connect B1, B2, B3 in series 8.  Connect B1and B3 in series S1 =  Closed S4 =  Closed S1 =  Closed S4 =  Open S2 =  Open S5 =  Open S2 =  Open S5 =  Closed left S3 =  Closed S3 =  Open

 4.  Connect B1and B2 in parallel 9.  Connect B1 and B3 in parallel S1 =  Closed S4 =  Closed S1 =  Closed S4 =  Open S2 =  Closed S5 =  Closed right S2 =  Closed S5 =  Closed right S3 =  Open S3 =  Closed

 5.  Connect B1, B2, B3 in parallel 10.  Connect B1 and B2 in series S1 =  Closed S4 =  Closed Impossible: to just connect these two bulbs in series since S2 =  Closed S5 =  Closed right you must go through B3 to get back to the battery.  B1, B2, S3 =  Closed and B3 can be connected in series, not just B1 and B2.