Which one of the following statements regarding Ohm`s law is not correct?

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Q: (NDA-II/2019)

Which one of the following statements regarding Ohm's law is not correct?

question_subject: 

Science

question_exam: 

NDA-II

stats: 

0,8,16,7,6,3,8

keywords: 

{'material obeys ohm': [0, 0, 0, 1], 'resistance': [0, 0, 1, 2], 'conductor': [0, 0, 1, 2], 'law': [0, 0, 0, 1], 'electric field': [0, 0, 0, 1], 'homogeneous materials': [0, 0, 0, 1], 'applied potential difference': [0, 0, 0, 1], 'potential difference': [0, 0, 1, 0], 'polarity': [0, 0, 0, 3], 'ohm': [0, 0, 1, 2], 'assumption': [0, 0, 0, 2]}

Option 1: This statement correctly explains Ohm`s law. According to Ohm`s law, the current flowing through a conductor is directly proportional to the potential difference (voltage) applied.

Option 2: This statement is also correct. Ohm`s law states that a conducting device obeys it when the resistance of the device remains constant regardless of the magnitude and polarity of the applied potential difference.

Option 3: This statement is correct as well. Ohm`s law applies to conducting materials when their resistance remains constant regardless of the magnitude and direction of the applied electric field.

Option 4: This is the incorrect statement in regards to Ohm`s law. Ohm`s law does not apply uniformly to all materials. Only certain materials, known as "ohmic" or "homogeneous" materials, obey Ohm`s law under certain conditions. Homogeneous materials exhibit a linear relationship between current and voltage, independent of the strength of the electric field or the presence of any other fields. However, certain materials like diodes and other non-linear elements do not follow Ohm`s law.

Alert - correct answer should be: 4