Ohm's law is valid only for
Correct answer: C. Metals
- A. Thermistor
- B. Bulb filament
- C. Metals
- D. Semiconductors
Explanation
Ohm's law is valid for metallic conductors because they have a linear relationship between current and voltage. This makes Option C, 'Metals', the correct answer. Thermistors, bulb filaments, and semiconductors do not follow this linear relationship and hence Ohm's law is not valid for them.
This question appeared on the ETEA MDCAT 2013 paper, which you can sit online with every answer explained.
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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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