Ohm's law is valid only for currents following in:
Correct answer: A. Metallic conductor
- A. Metallic conductor
- B. Transistors
- C. Diodes
- D. Electric arcs
Explanation
Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points, assuming the temperature remains constant. This linear relationship (I = V/R) is valid primarily for metallic conductors. In contrast, transistors and diodes are semiconductor devices and exhibit nonlinear current-voltage characteristics, which means they do not follow Ohm's law. Electric arcs involve ionized gases (plasma), which also do not adhere to linear Ohmic behavior.
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About Resistance and Resistivity
Resistance measures opposition to current in a conductor and follows R = V/I for an ohmic conductor, while resistivity is an intrinsic property of the material. Questions use R = ρL/A, examine effects of length, cross-sectional area and temperature, and distinguish resistance, resistivity, conductance and conductivity.
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