Solving Unit and Quantity Analogies: Ohm and Newton

This question presents an analogy based on the relationship between a physical quantity and its SI unit. The pattern established on the left side of the (::) symbol must be applied to the right side to find the missing term.

Analyzing the Given Analogy Pair: Ohm : Electric Resistance

The first pair is "Ohm : Electric Resistance". Let's identify the relationship here:

• Ohm ($\Omega$) is the SI unit used to measure Electric Resistance.
• Electric Resistance is the physical quantity being measured.

So, the relationship is: SI Unit : Physical Quantity.

Applying the Relationship to the Second Pair: Newton : ?

We are given "Newton : ?" and need to find the physical quantity for which Newton is the SI unit, following the same SI Unit : Physical Quantity pattern.

• Newton (N) is a well-known SI unit.
• We need to determine which physical quantity is measured in Newtons.

Evaluating the Options

Let's examine each provided option to see which one corresponds to the physical quantity measured in Newtons:

1. Force: Force is a physical quantity that describes the interaction which, when unopposed, will change the motion of an object. The SI unit of Force is indeed the Newton (N). This matches our required relationship.
2. Pressure: Pressure is defined as force per unit area. The SI unit of Pressure is the Pascal (Pa), which is equivalent to one Newton per square meter ($\text{N/m}^2$). So, Newton is not the unit for Pressure.
3. Temperature: Temperature is a physical quantity expressing the degree of hotness or coldness of a substance or environment. The SI unit of Temperature is Kelvin (K). So, Newton is not the unit for Temperature.
4. Area: Area is the measure of the extent of a surface. The SI unit of Area is the square meter ($\text{m}^2$). So, Newton is not the unit for Area.

Identifying the Correct Quantity for Newton

Based on our analysis, Newton (N) is the SI unit for Force. Therefore, the relationship "Newton : Force" follows the same pattern as "Ohm : Electric Resistance".

Conclusion

The analogy is based on the SI unit and the quantity it measures. Since Ohm is the SI unit for Electric Resistance, Newton is the SI unit for Force.

Revision Table: Common SI Units and Quantities

Additional Information on SI Units and Physics Concepts

The International System of Units (SI) is the modern form of the metric system and is the most widely used system of measurement. It is built upon a set of seven base units, from which all other units (derived units) are constructed.

Base SI Units

• Meter (m) for length
• Kilogram (kg) for mass
• Second (s) for time
• Ampere (A) for electric current
• Kelvin (K) for thermodynamic temperature
• Mole (mol) for amount of substance
• Candela (cd) for luminous intensity

Derived SI Units

Derived units are formed by combining base units according to the algebraic relations linking the corresponding quantities. For example:

• The unit of Force, the Newton (N), is derived from mass (kg), length (m), and time (s) using Newton's second law ($\text{F} = \text{ma}$). Thus, $1 \text{ N} = 1 \text{ kg} \cdot \text{m}/\text{s}^2$.
• The unit of Electric Resistance, the Ohm ($\Omega$), is derived from voltage (V) and current (A) using Ohm's law ($\text{V} = \text{IR}$). It can also be expressed in terms of base units.
• The unit of Pressure, the Pascal (Pa), is derived from force (N) and area ($\text{m}^2$). Thus, $1 \text{ Pa} = 1 \text{ N/m}^2$.

Understanding the relationship between physical quantities and their standard units like Ohm for Electric Resistance and Newton for Force is fundamental in physics and helps in solving such analogy-based questions.