1. A Junior Hard Service Cord is known as an (SO-Type) (SJO-Type) cord. 2. You disconnect a cord by (jerking it from the socket) (grasping plug and pulling it out). 3. Brass sockets are unsafe because (they break too easily) (the exposed metal can cause short circuits). 4. Rubber-covered cord is safer for emergency cords than fabric because (it will stretch) (it will insulate and protect the wires inside). 5. In a trouble light (any kind of bulb will do) (a rough service bulb is best). Ideas for Demonstrations and Exhibits 1. Show how to make your trouble light and a method of storing it. 2. Show a safe trouble light, and an unsafe trouble light with danger points marked. 3. Show cutaway pieces of different types of cord. For More Information Ask your power supplier, county highway engineer, police official or leader to tell you about various types of portable emergency lights and their uses. LESSON NO. B-5 Credit Points 5 WHAT MAKES MOTORS RUN What makes an electric motor run? Can you make an electric motor that will run? Certainly you can, and by doing so you'll learn why it runs. It won't be mysterious any more and you'll be ahead of all the millions of people who use motors every day and never know why or how the motor converts electrical energy into useful power. [Illustration] Motors Are Magnets You know how one end of a compass needle always points to North. No matter how you turn the compass, the same end of the needle always swings to the North. The earth itself and that small compass are both magnets (Figure 1). Each has a North pole and a South pole. Around the poles of each there are magnetic fields, invisible lines of force that attract and repel. [Illustration: Figure 1. The same end of the compass needle always points to the earth's magnetic North Pole.] The N poles _repel_ each other and so do the S poles. The N and S poles _attract_ each other. In other words, opposite poles attract; poles that are alike repel each other. Lay 2 bar magnets on a table side-by-side. If both N poles are at one end, they'll repel each other and almost flip around until there's a N pole lying next to a S pole (Figure 2). [Illustration: Figure 2. Small bar magnets laid side by side move so that the North pole of one is near the South pole of the other.] Now suppose we place one of the bar magnets on the table. The other, we'll fix on a pivot so it can spin around. This one we'll move so its N pole almost touches the fixed magnet's N pole. As soon as we release it, the movable magnet will spin around so its S pole will be near the N pole of the stationary magnet. That's an electric motor--almost. [Illustration: Figure 3. A movable bar magnet pivots so its South pole is near the North pole of a stationary magnet.]