MCQ Detailed View

Resistance is a measure of how much a material opposes the flow of electric current. It is measured in ohms (Ω), named after the German physicist Georg Simon Ohm, who formulated Ohm’s law. Electrical components such as resistors are rated in ohms, kilohms (kΩ), and megaohms (MΩ) depending on the magnitude of resistance.

A megaohm (MΩ) is a unit of resistance equal to one million ohms (10⁶ Ω). The prefix “mega” in the metric system denotes 1,000,000, making it easy to convert between ohms, kilohms, and megaohms. For example, 1 kΩ = 1,000 Ω, and 1 MΩ = 1,000 kΩ = 1,000,000 Ω.

Understanding these conversions is important in physics and electronics, because electrical circuits often use components with a wide range of resistances. High resistance values like megaohms are common in applications such as voltage dividers, insulation resistance testing, and high-impedance circuits, whereas lower resistances are used in devices that require higher current flow.

Mathematically, the conversion is straightforward:

1 MΩ=1,000,000 Ω=106 Ω1\ \text{MΩ} = 1,000,000\ \text{Ω} = 10^6\ \text{Ω}1 MΩ=1,000,000 Ω=106 Ω

Incorrect options, such as 10⁸ or 10⁻⁶ ohms, represent other orders of magnitude and do not match the definition of a megaohm. Knowing the proper value helps in calculations of current, voltage, and power in circuits using Ohm’s law: $V=IR$.

This question falls under Physics, specifically electricity and electrical units, and is a key concept in everyday science. Learning about resistance units helps students accurately analyze circuits and understand electrical measurements in real-world applications.