Electric field lines:

CONCEPT:

Electric field lines:

• An electric field line is an imaginary line along which a positive test charge will move if left free.
• Electric field lines are drawn to represent the electric field.

Properties of electric field lines:

1. Electric field lines start from positive charges and end at negative charges. If there is a single positive charge then electric field lines start from positive charge and end at infinity. Similarly, if there is a single negative charge then electric field lines start from infinity and end at a negative charge.
2. In a charge-free region, electric field lines can be taken to be continuous curves without any breaks.
3. The tangent at any point on the electric field line gives the direction of the electric field at that point.
4. Electric field lines due to a point charge never intersect each other.
5. The electric field lines never form a closed loop.
6. The density of the electric field lines at a point indicates the strength of the electric field at that point.

EXPLANATION:

• From the above, it is clear that electric field lines start from positive charges and end at negative charges. 
• So, the electric field lines never form a closed loop. Hence, option 1 is correct.