Part 1 (2/2)

_Circuits_--A closed circuit is one in which the electricity is flowing, lighting a light, running a motor, or some other appliance The circuit runs all the way froenerated to your hoenerator

Circuits are opened and closed by switches When the circuit is opened, the electricity stops at the switch Before working on a switch, socket, fuse, or any part of the wiring be sure to open the main switch The main switch is usually at the fuse box or near it Appliances should be disconnected when you work on them Everyone in the family should knohere the main switch is so it can be pulled in case of accidents, fire, flood, or windstore

_Fuses and Circuit Breakers_--These are the safety valves of your electrical system The different electrical circuits in your home are meant to carry only certain amounts of electricity Some carry only 15 amps, others can carry 20 or more They are marked to show capacity

When a fuse burns out or a circuit breaker opens, look for an overload of lights and appliances on the circuit before you try to replace the fuse or close the circuit breaker Without these safeguards, the overloaded electric line will heat up and may start a fire Even if no fire starts, electricity will be wasted and the hoood

Remember: If you ever have to replace a fuse, pull the ht handy in your house It seeht, and it doesn't pay to stumble or fumble around electric wires in the dark

WHAT TO DO: Make A Circuit Board

So that you can show others how electricity travels from here to there, and how it behaves under different conditions, make an electric circuit board

_Materials Needed:_

Piece of 3/4” board about 4” x 6”

l-l/2-volt No 6 dry cell battery Two pieces of bell wire, each 24” long, one black, one white Two 10-penny box nails (3”) Three 3-penny box nails (1”) Two small screws or carpet tacks Two 2-inch rubber bands Two miniature sockets with solder terht bulbs

_Tools Needed:_ Ruler, pencils, ha the Board:_

1 Lay out the board with a pencil and ruler as indicated in Figure 1

2 Bend the three-inch nail as shown in Figure 2, using pliers, vise and hammer

3 Pound the one-inch nails into the board for a half-inch at points A, C, and D Use the three-inch nail to make a hole a half-inch deep at B

Put the crank nail in this hole and pound in a little farther Attach the lamp socket brackets at E and F Stretch the rubber band as in Figure 3

4 Lay out the electricity path, the circuit (Figure 3) Use the black wire for the positive side of the circuit (the center pole of battery)

Twist it around the switch crank B, and the center pole of battery Run another piece to the outside terative pole of battery froure 1 (Circuit Board)]

[Illustration: Figure 2 (Switch)]

5 Close the switch The rubber band should hold the switch nail tightly against nail at C Does the bulb light? __________ If it doesn't, check the connections

Now you have a circuit--a closed circuit when the electricity runs all the way froative pole The black wire is the hot side, the live wire, because it carries the full load of the battery up to the bulb

Remember, battery current is direct current, DC In the case of alternating current, AC, such as s use, the electricity flows in first one direction and then the other