Understanding Analogies: Resistance and Energy Units

The question asks us to find a word that relates to 'Energy' in the same way that 'Ohm' relates to 'Resistance'. This is a type of analogy question where we need to identify the relationship between the first pair of words and apply the same relationship to the second pair.

Analyzing the First Pair: Resistance and Ohm

The first pair of words is 'Resistance' and 'Ohm'. We need to determine the relationship between these two terms.

• Resistance: In physics, electrical resistance is a measure of the opposition to current flow in an electrical circuit.
• Ohm: The ohm (\(\Omega\)) is the SI derived unit of electrical resistance. It is named after German physicist Georg Simon Ohm.

The relationship between Resistance and Ohm is that Ohm is the standard unit of measurement for Resistance.

Applying the Relationship to Energy

Now, we apply the same relationship to the second term, 'Energy'. We need to find the standard unit of measurement for Energy.

• Energy: In physics, energy is the quantitative property that must be transferred to a body or a physical system to perform work on, or to heat, the body or system.

The standard SI unit for measuring Energy is the Joule.

Evaluating the Options for Energy Unit

Let's look at the given options and see which one is the unit of Energy:

1. Joule: The Joule (J) is the SI derived unit of energy, work, or amount of heat. This matches the unit of Energy.
2. Mho: The mho (or siemens) is a unit of electrical conductance, which is the reciprocal of electrical resistance. This is not a unit of Energy.
3. Mole: The mole (mol) is the SI base unit of amount of substance. This is not a unit of Energy.
4. Ampere: The Ampere (A) is the SI base unit of electric current. This is not a unit of Energy.

Determining the Correct Analogy Completion

Since Ohm is the unit of Resistance, the word that completes the analogy Energy : ? must be the unit of Energy. The unit of Energy is Joule.

Therefore, the analogy is: Resistance : Ohm :: Energy : Joule.

Summary of Relationship

The correct option is Joule.

Revision Table: Common Physical Quantities and Units

Additional Information on Energy and Units

While Joule is the standard SI unit for Energy, energy can also be measured in other units depending on the context. Understanding different units is important for various applications.

• Calorie: Often used for heat energy, especially in the context of food and nutrition. 1 calorie is approximately 4.184 Joules.
• Kilowatt-hour (kWh): Commonly used for electrical energy billing. 1 kWh is the energy consumed by a device of 1 kilowatt power running for 1 hour. 1 kWh = 3.6 \(\times\) 10⁶ Joules.
• Electronvolt (eV): Used in particle physics and nuclear physics to measure the energy of particles. 1 eV is the energy gained by an electron moving through an electric potential difference of 1 volt. 1 eV \(\approx\) 1.602 \(\times\) 10^-19 Joules.
• Erg: A unit of energy used in the CGS (centimetre–gram–second) system. 1 erg = 10^-7 Joules.

Understanding the relationships between different units helps in solving problems involving energy conversions.