Question

One ohm is equal to
(A) $ {10^6}M\Omega $
(B) $ {10^9}M\Omega $
(C) $ {10^{ - 6}}M\Omega $
(D) None of the above

Answer 1

Hint
Mega is used as a unit prefix in metric systems of units denoting a factor of one million ( $ {10^6} $ ). Mega is represented by the symbol $ M $ . As the relation between ohm and megaohm is known, we find how much one ohm is equal to.

Complete step by step answer
From the definition of Mega, $ 1M\Omega = {10^6}\Omega $ from this,
One ohm is, $ \dfrac{{1\Omega }}{{{{10}^6}\Omega }} \times 1M\Omega = {10^{ - 6}}M\Omega $
 $ \therefore 1\Omega = {10^{ - 6}}M\Omega $
Hence, one ohm is equal to $ {10^{ - 6}}M\Omega $
Option (C) $ {10^{ - 6}}M\Omega $ is the correct answer.

Additional information
One ohm is defined as an electrical resistance between two points of a conductor when a constant potential difference of one volt, applied to these points, produces in the conductor a current of one ampere.
The cgs unit of resistance is called abohm which is equal to one billionth of an ohm. One abohm is defined as the resistance of a conductor when a constant potential difference of one abvolt, applied to its terminals, produces a current of one abampere in the conductor.
 $ 1ohm = {10^{ - 9}}abohm $
The resistance can be measured using ohmmeter. This is commonly found in all multimeters. To know the value of resistance, first disconnect all voltage sources from the circuit; then touch ohmmeter’s two probes to ends of the circuit and find the value of resistance.

Note
One should note that in this question it is asking how many Megaohms will be present in 1ohm so the power of 10 will be negative as Megaohms are much greater than ohm so we need to divide 1Megaohm by $ {10^6} $ to make it equal to 1ohm.