If the potential difference across a resistor is doubled:
Correct answer: A. Only the current is doubled
- A. Only the current is doubled
- B. Only the current is halved
- C. Only the resistance is doubled
- D. Only the resistance is halved
Explanation
The correct answer is that only the current is doubled. According to Ohm's law (V = IR), the current through a resistor is directly proportional to the potential difference across it, provided the resistance remains constant. Therefore, if the potential difference is doubled, the current must also be doubled to maintain this relationship. The resistance of the resistor does not change with variations in potential difference or current, as it is an inherent property of the material.
This question appeared on the ETEA MDCAT 2016 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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