Which one of the following is not a fundamental quantity ?

Options

A. Temperature
B. Eleetric current
C. Pressure
D. Length

Answer

To determine which of the following is not a fundamental quantity, we first need to understand what fundamental quantities are. Fundamental quantities are those that cannot be expressed in terms of other quantities. In physics, there are seven fundamental quantities:

1. Mass (M)
2. Length (L)
3. Time (T)
4. Temperature (Θ)
5. Electric Current (I)
6. Amount of Substance (N)
7. Luminous Intensity (J)

Now, let's analyze the options provided:

1. Temperature - This is a fundamental quantity.
2. Electric Current - This is also a fundamental quantity.
3. Length - This is another fundamental quantity.
4. Pressure - This is not a fundamental quantity.

To understand why pressure is not a fundamental quantity, we can express it in terms of other quantities. Pressure is defined as force per unit area. The formula for pressure (P) is given by:

\[ P = \frac{F}{A} \]

Where:
- \( F \) is the force
- \( A \) is the area

Now, we can express force in terms of fundamental quantities. The dimension of force is given by:

\[ F = m \cdot a \]

Where \( a \) (acceleration) can be expressed as:

\[ a = \frac{L}{T^2} \]

Thus, the dimension of force can be expressed as:

\[ [F] = [M][L][T^{-2}] \]

Now, the area \( A \) is given by:

\[ A = L^2 \]

So, the dimension of pressure can be expressed as:

\[ [P] = \frac{[F]}{[A]} = \frac{[M][L][T^{-2}]}{[L^2]} = [M][L^{-1}][T^{-2}] \]

This shows that pressure depends on mass, length, and time, which means it is derived from these fundamental quantities.

Therefore, the correct answer to the question "Which one of the following is not a fundamental quantity?" is:

**Pressure** (Option number 4).