One of the following is not a property of field lines

Options

A. field lines are continuous curves without any breaks
B. two field line cannot cross eac outer
C. field lines start at positive charges and end at negative charges
D. they form closed loops

Answer

To determine which of the following options is not a property of electric field lines, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding Field Lines**: Electric field lines are visual representations of electric fields. They indicate the direction and strength of the electric field created by electric charges.

2. **Option A: Continuous Curves Without Breaks**:
- Field lines are indeed continuous curves. They do not have breaks or gaps. This is because the electric field exists throughout the space around the charge.
- **Conclusion**: This option is a property of field lines.

3. **Option B: Two Field Lines Cannot Cross Each Other**:
- If two field lines were to cross, it would imply that at the point of intersection, there are two different directions of the electric field. This is not possible, as the electric field at a point can only have one direction.
- **Conclusion**: This option is also a property of field lines.

4. **Option C: Field Lines Start from Positive Charges and End at Negative Charges**:
- Electric field lines originate from positive charges and terminate at negative charges. This is a fundamental property of electric fields.
- **Conclusion**: This option is a property of field lines.

5. **Option D: They Form a Closed Loop**:
- Electric field lines do not form closed loops. They start from positive charges and end at negative charges. They do not return to the same charge or form a loop.
- **Conclusion**: This option is NOT a property of field lines.

### Final Answer:
The option that is not a property of field lines is **Option D: They form a closed loop**.

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