The Working of Wires
Section 1 WHAT IS HAPPENING IN THE WIRES?
INTRODUCTION Electricity is usually invisible. Except for lightning and sparks, you never see it in daily life. However, light bulbs and a magnetic compass can show you when something electrical is happening. By observing their behavior and making a few assumptions, you can begin forming ideas about electricity. This type of thinking is called “building a model”. INVESTIGATION ONE: WHAT IS NEEDED TO LIGHT A BULB? 1.1 Activity: Lighting bulbs in a loop Insert three D-cells into the battery holder (as in Figure 1.1), and insert two ROUND bulbs (not long bulbs) into a pair of sockets. Use three wires to connect the sockets to each other and to the two “terminals” of the battery holder: 1) the spring inside the case near the red spot, and 2) the metal post on the outside of the case near the blue spot. The bulbs should light and be of similar brightness. The battery, bulbs and wires now form a “closed loop”.
Black Plastic Battery Case
Blue Spot on Case
Connect wire to Spring Wire Round Bulb in Socket
Wire
Wire
Figure 1.1 BASIC CLOSED LOOP
Round Bulb in Socket
1. “Break” the loop by disconnecting a wire from one end of the battery holder; then reconnect the loop. Do you see both bulbs light at exactly the same time? Do you believe that both bulbs actually light at the same time? Do both bulbs appear to go out at exactly the same time? (We will return to this question later; for now, just report your observations as well as possible.)
2. Reconnect the wire to the battery, and then disconnect a different wire somewhere else in the loop. Try doing this in several places. Be sure that you have only one break in the loop at a time. Is there any place where you can break the loop and one or both of the bulbs will still stay lit?
PASCO scientific Student Manual 1
3. Unhook any wire and then bring it back as close as you can to where it was connected — without actually making contact. Do this slowly and
INTRODUCTION Electricity is usually invisible. Except for lightning and sparks, you never see it in daily life. However, light bulbs and a magnetic compass can show you when something electrical is happening. By observing their behavior and making a few assumptions, you can begin forming ideas about electricity. This type of thinking is called “building a model”. INVESTIGATION ONE: WHAT IS NEEDED TO LIGHT A BULB? 1.1 Activity: Lighting bulbs in a loop Insert three D-cells into the battery holder (as in Figure 1.1), and insert two ROUND bulbs (not long bulbs) into a pair of sockets. Use three wires to connect the sockets to each other and to the two “terminals” of the battery holder: 1) the spring inside the case near the red spot, and 2) the metal post on the outside of the case near the blue spot. The bulbs should light and be of similar brightness. The battery, bulbs and wires now form a “closed loop”.
Black Plastic Battery Case
Blue Spot on Case
Connect wire to Spring Wire Round Bulb in Socket
Wire
Wire
Figure 1.1 BASIC CLOSED LOOP
Round Bulb in Socket
1. “Break” the loop by disconnecting a wire from one end of the battery holder; then reconnect the loop. Do you see both bulbs light at exactly the same time? Do you believe that both bulbs actually light at the same time? Do both bulbs appear to go out at exactly the same time? (We will return to this question later; for now, just report your observations as well as possible.)
2. Reconnect the wire to the battery, and then disconnect a different wire somewhere else in the loop. Try doing this in several places. Be sure that you have only one break in the loop at a time. Is there any place where you can break the loop and one or both of the bulbs will still stay lit?
PASCO scientific Student Manual 1
3. Unhook any wire and then bring it back as close as you can to where it was connected — without actually making contact. Do this slowly and