Introduction to Conductors, Insulators, and Electric Circuits

Conductors and Insulators



Electric Circuits

Charges will tend to flow from one terminal to the other if an external conducting path, i.e. circuit, is provided.
In addition to an energy source and a conducting path, a circuit also includes some resistance to the current.
Electric current (I) is then the flow of electric charge. By definition, the direction of the electric current is the direction of flow of positive charge.
The flow is measured with respect to time. Hence, electric current is the rate of flow of electric charge.
Example 1:
Assume 6 C of charge flow through a wire in 4 s, then the electric current I is 6 C / 4 s = 1.5 A.

Example 2:
Two arrangements of a battery, bulb, and wire are shown below.
Question: Which of the two arrangements will light the bulb?
Pick an answer:
  1. Arrangement (A)
  2. Arrangement (B)
  3. Neither
  4. Both
In arrangement B, voltage does not exit across the filament and therefore no current flows in the filament.
However, in the arrangement A, the bulb will light because the filament of the bulb is connected to the two sides of the battery to make a closed circuit.

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Date of last modification: Summer , 2019