Which of the following physical quantities has neither units nor dimensions?

Options

A. Angle
B. Lumnous intensity
C. Coefficient of friction
D. Current

Answer

To determine which of the following physical quantities has neither units nor dimensions, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Identify the Physical Quantities:**
We have four physical quantities to consider:
- Angle
- Luminous Intensity
- Coefficient of Friction
- Current

2. **Analyze Each Quantity:**
- **Angle:**
- **Units:** Measured in degrees or radians.
- **Dimensions:** Dimensionless (it is a ratio of lengths).
- Conclusion: Angle has units (degrees/radians) but is dimensionless.

- **Luminous Intensity:**
- **Units:** Measured in candela (cd).
- **Dimensions:** It has dimensions (represented as J).
- Conclusion: Luminous intensity has both units and dimensions.

- **Coefficient of Friction:**
- **Units:** It is a ratio of two forces (frictional force to normal force), hence it is unitless.
- **Dimensions:** It is also dimensionless since it is a pure ratio.
- Conclusion: Coefficient of friction has neither units nor dimensions.

- **Current:**
- **Units:** Measured in amperes (A).
- **Dimensions:** It has dimensions (represented as A).
- Conclusion: Current has both units and dimensions.

3. **Final Conclusion:**
After analyzing all the physical quantities, we find that the **coefficient of friction** is the only quantity that has neither units nor dimensions.

### Answer:
The physical quantity that has neither units nor dimensions is the **coefficient of friction**.

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