An understanding of Ohm's Law is the basis for understanding circuits. This law is simply a statement that in order to increase the current passing through a device the voltage driving the current must increase proportionally. The constant of proportionality is called the resistance. While this is a good approximation of real circuits, in many cases it fails to consider devices like incandescent lamps and semi conductor devices like diodes, which have an explicitly non linear relationship between current and voltage. This leaves aside considerations of the temperature coefficient of resistivity, which forms the operating basis of the electrical thermocouples, and the strange behavior of resistance at very low temperatures giving us super conductors.
To complete this discussion activity:
Write an initial response to the following three discussion prompts. Post your response to the discussion board.
- With respect to Ohm's Law, explain in your own words what is meant when it is said that there is "a linear response between voltage and current." Name a specific device in which Ohm's Law is not a good description of the relationship between current and voltage. Do your best to explain this failure in terms of the basic properties of electrons flowing through a conducting material.
- Describe the temperature response of resistors in a circuit. Are there any devices which take advantage of this property? If so, explain how they work in terms of the properties of electrons.