Question 109: Current Electricity

Question

Which one of the following is not a measurable quantity?

Accepted Answer

Resistance is a physical property of a conductor that opposes current. It is easily measured using an Ohmmeter or by calculating the ratio of voltage to current ( $\mathrm{R}=\mathrm{V} / \mathrm{I}$ ). Hence, option (A) is not the correct option.
The voltage of a single point is representing the electric potential of that point which is defined as the work done to move a unit charge from infinity to a specific point.
Since infinity is an arbitrary reference point, the absolute value of voltage at a single point cannot be measured directly. It is a mathematical construct. So, voltage cannot be measured, i.e., not a measurebale quantity. Hence, option is (D) is the correct option.
Voltage difference (Potential difference) is the difference in electric potential between two specific points. This is measured by a voltmeter. So, it is a measurable quantity. Hence, option (B) is not the correct option.
Displacement current is a quantity appearing in Maxwell's equations, representing a changing electric field (like between the plates of a capacitor). While it isn't a flow of charges like normal current, its magnetic effects are real and can be measured using magnetic sensors. Hence, it is a measurable quantity. So option (C) is not the correct option.
Therefore, the correct option is (D).

Answer

Resistance

Answer

Voltage difference

Answer

Displacement current

Answer

Voltage

Current Electricity

Which one of the following is not a measurable quantity?

Choose the correct answer: