Which of the following is a scalar quantity ?

Options

A. electric current
B. electric field
C. acceleration
D. linear momentum

Answer

To determine which of the following is a scalar quantity, we need to analyze each option provided:

1. **Electric Current (I)**:
- Electric current is defined as the flow of electric charge. It has only magnitude (measured in Amperes) and does not have a direction associated with it.
- When two currents meet at a junction, the resultant current is the algebraic sum of the currents entering and leaving the junction. This property confirms that electric current behaves as a scalar quantity.

2. **Acceleration (a)**:
- Acceleration is defined as the change in velocity per unit time. It is calculated as \( a = \frac{\Delta v}{\Delta t} \).
- Here, \( \Delta v \) (change in velocity) is a vector quantity (it has both magnitude and direction), while \( \Delta t \) (time) is a scalar. Therefore, acceleration is a vector quantity.

3. **Linear Momentum (p)**:
- Linear momentum is defined as the product of mass and velocity, expressed as \( p = m \cdot v \).
- Mass (m) is a scalar quantity, but velocity (v) is a vector quantity. Since the product of a scalar and a vector is a vector, linear momentum is also a vector quantity.

4. **Electric Field (E)**:
- The electric field is defined as the force per unit charge, expressed as \( E = \frac{F}{q} \).
- Here, force (F) is a vector quantity, and charge (q) is a scalar. Thus, the electric field is also a vector quantity.

After analyzing all the options, we conclude that:

**The scalar quantity among the options is Electric Current.**

### Steps Summary:
1. Analyze Electric Current: Confirmed as scalar.
2. Analyze Acceleration: Confirmed as vector.
3. Analyze Linear Momentum: Confirmed as vector.
4. Analyze Electric Field: Confirmed as vector.
5. Conclusion: Electric Current is the only scalar quantity.