WIKI                                                ELECTRICITY

In this lab you will learn about:

LAB  OVERVIEW:
1.  EXERCISE 1:  SERIES CIRCUITS
2.  EXERCISE 2:  PARALLEL CIRCUITS
2.  EXERCISE 3:  V/R = I

RELEVANT HYPOTHESIS: ELECTRICITY IN A BAG
1. Electrical charge is conserved; charge is neither created nor destroyed.
2. Electrons move, but move slowly in a direct current.
3. When a circuit is turned on, the electrical field moves at the speed of light.
4. Current flows only when a circuit is complete.  No "ground", no flow.
5. There is no current unless there is a difference in potential (Voltage) between the poles.
6. The longer the conducting material (wire), the greater the resistance.
7. The thicker the wire, the less the resistance.

Be sure you have read the lecture on electricity.  The materials list is below.
 
EXERCISE 1:  SERIES
SERIES CIRCUIT
MATERIALS: D cell batteries, battery holders, Xmas lights, switch, buzzer, motor, alligator clips


The wire on the left is sufficiently stripped. 

METHODS: First you need to "strip" some of the plastic off the ends of the wire of the Xmas lights.  You only NEED to do this on one side as the alligator clips will make contact.  Hold the blade at a very oblique angle to the wire 
METHODS: SERIES CIRCUITS
1. Construct simple circuit with a light like at the left.  Now add a switch and turn it on and off. 
Then add the little motor (some may not have one).

2. Now keep adding lights, etc until something happens, like the motor slowing or stopping, the lights dimming, the buzzer weakens.  What has happened? 

Take a picture of your actual completed circuit, label it "series" and place in your lab wiki

3. When you have more than one item on the circuit,  disconnect the one furthest from the battery and explain what happens. 

4. Draw one circuit, label it and include a KEY showing each symbol and what it means along one edge of the page (or use a draw program if you have one.).  Find or create a symbol for the little motor. Then take a picture of this and put this into your lab wikibook.  Please be sure to take a good picture, straight on and light enough for me to clearly see the details. 

Go online and google for more pictures of series circuits (look in images) if you arent sure what they are or still dont know what the difference is with parallel circuits.


 SERIES CIRCUIT                 PARALLEL CIRCUIT                        ELECTRICAL SYMBOLS

 
EXERCISE 2:  PARALLEL CIRCUITS
PARALLEL CIRCUIT
 
METHODS: PARALLEL CIRCUITS
1.  Go back to step 2 and repeat the steps, but this time connect them in parallel circuits.  Does this change anything?

2. When you have more than one item on the circuit, disconnect the one furthest from the battery and explain what happens. 

3. Draw one circuit, label it and include a KEY showing each symbol and what it means along one edge of the page.  Find or create a symbol for the little motor. Then take a picture of this and put this into your lab wikibook.  Please be sure to take a good picture, straight on and light enough for me to clearly see the details.  Draw each circuit you assemble, label it and explain how an electrical circuit works. 
 

Take a picture of your actual completed circuit, label it "parallel" and place in the drop box. 

 


 
EXERCISE 3:  V/R = I
MATERIALS: Computer

METHODS:
Go to ELECTRICITY FUNDAMENTALS http://zebu.uoregon.edu/nsf/circuit.html#Ohm
and run the tests.  Report the results in your wikibook

2. RESISTANCE.  Watts are a rating of "work" done by electricity.  Discuss how much "work" it was for you to get the different bulbs to light.

3. Discuss the relationship between voltage, resistance and amperage.  Why are people always warned about not plugging too many items into typical electrical extension cords?

You have a small freezer too far away from the plug.  You use a typical extension cord, but the cord feels warm or hot when the freezer is plugged in.  Now what do you do?

Reproduce these tables in your wikibook. 

How much resistance is needed to light the bulb in trial 1?

 
Voltage of the battery Resistance Amperage of  the bulb
6    
12    
18    
24    
How much resistance is needed to light a 3 amp bulb in trial 2?
 
Voltage of the battery Resistance Amperage of the bulb
15   3
30   3
45   3
60   3


How much resistance is needed to light a 3 amp bulb in trial 2?

 
Voltage of the battery Resistance Amperage of the bulb
28   4
56   4
84   4
112   4
Calculate these given that the bulb lights and doesn't blow
 
Voltage of the battery Resistance Amperage of the bulb
28   2
56   10
  10 4
6   0.5
What happens if too much current reaches the light bulb?
 If insufficient current reaches the light bulb?
What satisfies OHMs laws?
A light bulb breaks off in a lamp socket. How do you get it out without cutting yourself?

MATERIALS
 
LAB 6: ELECTRICITY (in the bag)
we supply: 
wire alligator clips switch battery holder 
buzzers motor lights
D battery or 2 D batteries if you have a double
CLICK ON ANY OF THESE FOR LARGER PIC