Which of the following is a vector quantity ?

Options

A. Temperature
B. Flux density
C. Pressure
D. Time

Answer

To determine which of the following is a vector quantity, we need to analyze each option provided in the question. A vector quantity is defined as a quantity that has both magnitude and direction, while a scalar quantity has only magnitude.

### Step-by-step Solution:

1. **Identify the quantities given**: We need to analyze the following quantities: temperature, flux density, pressure, and time.

2. **Analyze Temperature**:
- Temperature is a measure of the average kinetic energy of particles in a substance.
- It has only magnitude (e.g., 20°C) and no direction.
- **Conclusion**: Temperature is a scalar quantity.

3. **Analyze Flux Density**:
- Flux density refers to the amount of flux (electric or magnetic) passing through a unit area.
- While it involves a dot product (E·A or B·A), it is still a measure of how much field is passing through an area and does not have a specific direction associated with it in the same way vectors do.
- **Conclusion**: Flux density is a scalar quantity.

4. **Analyze Pressure**:
- Pressure is defined as force per unit area (P = F/A).
- It has a magnitude (the amount of force applied) and a direction (the direction in which the force is applied).
- **Conclusion**: Pressure is a vector quantity because it depends on the direction of the applied force.

5. **Analyze Time**:
- Time is a measure of the duration of events.
- It has only magnitude (e.g., 5 seconds) and no direction.
- **Conclusion**: Time is a scalar quantity.

6. **Final Conclusion**:
- Among the quantities analyzed, pressure is the only vector quantity.

### Answer:
The vector quantity among the options is **Pressure**.