The property of the electric line of force
(a) The tangent to the line of force at any point is parallel to the direction of .E. at that point
(b) No two lines of force intersect each other

Options

A. both .a & b.
B. only .a.
C. only .b.
D. a. (or) .b.

Answer

To solve the question regarding the properties of electric lines of force, we will analyze each statement provided in the question step by step.

### Step-by-Step Solution:

1. **Understanding Electric Lines of Force**:
- Electric lines of force are imaginary lines used to represent the electric field around charged objects. They help visualize the direction and strength of the electric field.

2. **Analyzing Statement (a)**:
- The statement says: "The tangent to the line of force at any point is parallel to the direction of the electric field (E) at that point."
- **Explanation**: At any point on an electric line of force, if you draw a tangent, this tangent will indicate the direction of the electric field at that point. This is because the electric field is defined as the force experienced by a positive test charge placed in the field, and the tangent shows the direction in which the force would act.
- **Conclusion**: This statement is **True**.

3. **Analyzing Statement (b)**:
- The statement says: "No two lines of force intersect each other."
- **Explanation**: If two lines of force were to intersect, it would imply that at the point of intersection, the electric field would have two different directions, which is not possible. Therefore, electric lines of force can never cross each other.
- **Conclusion**: This statement is also **True**.

4. **Final Conclusion**:
- Both statements (a) and (b) are true regarding the properties of electric lines of force.

### Final Answer:
Both statements (a) and (b) are correct.