Question

Joule/Coulomb represents :

• A. volt
• B. ampere
• C. watt
• D. ohm

Hint:

Remember the fundamental definitions:
{Volt (V)} = Work done (W) / Charge (Q) \(\rightarrow\) Unit: {Joule/Coulomb (J/C)}
Ampere (A) = Charge (Q) / Time (t) \(\rightarrow\) Unit: Coulomb/second (C/s)
Watt (W) = Work done (W) / Time (t) \(\rightarrow\) Unit: Joule/second (J/s)
Ohm (\(\Omega\)) = Voltage (V) / Current (I) \(\rightarrow\) Unit: Volt/Ampere (V/A) The question asks for Joule/Coulomb, which directly matches the unit for Volt.

Answer 1

The Correct Option is A

Concept: This question asks to identify the physical quantity represented by the unit Joule per Coulomb (J/C). We need to recall the definitions of various electrical quantities and their units. Step 1: Define the units involved
Joule (J): The SI unit of energy or work.
Coulomb (C): The SI unit of electric charge. So, Joule/Coulomb means Energy per unit Charge (or Work done per unit Charge). Step 2: Recall the definitions of the quantities in the options
Volt (V): The SI unit of electric potential difference (voltage) or electromotive force (emf). Electric potential difference (\(V\)) between two points is defined as the work done (\(W\)) per unit charge (\(Q\)) to move a charge from one point to another. \[ V = \frac{W}{Q} \] The unit of work (\(W\)) is Joule (J), and the unit of charge (\(Q\)) is Coulomb (C). Therefore, the unit of Volt is Joule/Coulomb (J/C).
Ampere (A): The SI unit of electric current (\(I\)). Current is the rate of flow of charge. \[ I = \frac{Q}{t} \quad (\text{Coulomb/second}) \]
Watt (W): The SI unit of power (\(P\)). Power is the rate at which work is done or energy is transferred. \[ P = \frac{W}{t} \quad (\text{Joule/second}) \] Also, \(P = VI\).
Ohm (\(\Omega\)): The SI unit of electrical resistance (\(R\)). From Ohm's Law, \(R = \frac{V}{I}\) (Volt/Ampere). Step 3: Identify the quantity represented by Joule/Coulomb From the definition of electric potential difference (voltage), its unit is Joule per Coulomb. Therefore, Joule/Coulomb represents volt.