What are the two things that must be done to make the bulb light up in the following case?
Answers
Answer:
Suppose that you were given a small light bulb, an electrochemical cell and a bare copper wire and were asked to find the four different arrangements of the three items that would result in the formation of an electric circuit that would light the bulb. What four arrangements would result in the successful lighting of the bulb? And more importantly, what does each of the four arrangements have in common that would lead us into an understanding of the two requirements of an electric circuit?
The activity itself is a worthwhile activity and if not performed before, one ought to try it before reading further. Like many lab activities, there is power in the actual engagement in the activity that cannot be replaced by simply reading about it. When this activity is performed in the physics classroom, there are numerous observations that can be made by watching a class full of students eager to find the four arrangements. The following arrangements are often tried and do not result in the lighting of the bulb.
After a few minutes of trying, several healthy chuckles, and an occasional exclamation of how hot the wire is getting, a couple of students become successful at lighting the bulb. Unlike the above attempts, the first successful attempt is characterized by the production of a complete conducting loop from the positive terminal to the negative terminal, with both the battery and the light bulb being part of the loop. As shown in the diagram at the right, the base of the light bulb connects to the positive terminal of the cell and the wire extends from the ribbed sides of the light bulb down to the negative terminal of the cell. A complete conducting loop is made with the light bulb being part of the loop. A circuit exists and charge flows along the complete conducting path, lighting the bulb in the process. Compare the arrangement of the cell, bulb and wire at the right to the unsuccessful arrangements shown above. In attempt A, the wire does not loop back to the negative terminal of the cell. In attempt B, the wire does form a loop but not back to the negative terminal of the cell. In attempt C, there is no complete loop at all. Attempt D resembles attempt B in that there is a loop but not from the positive terminal to the negative terminal. And in attempt E, there is a loop and it does go from positive terminal to negative terminal; this is a circuit but the light bulb is not included as part of it. CAUTION: Attempt E will cause your fingers to get hot as you hold the bare wire and charge begins to flow at a high rate between the positive and negative terminals.
Answer:
the circuit must be closed and two electric cells have to to join with each other