[amp_mcq option1=”A column of mercury” option2=”A cube of carbon” option3=”A cube of copper” option4=”The unit length of wire” correct=”option1″]
The correct answer is: A. A column of mercury.
The International ohm is defined as the resistance, expressed in ohms, of a column of mercury 106.3 cm long and 1 square millimeter in cross section, at the temperature of melting ice.
The other options are incorrect because:
- A cube of carbon is not used to define the International ohm.
- A cube of copper is not used to define the International ohm.
- The unit length of wire is not used to define the International ohm.