## **Electric Field Lines** ### **Definition** >Electric field lines (or lines of force) are imaginary lines used to represent the electric field around a charged body. These lines depict the path a unit positive test [[Charge]] would follow when placed in the field of a source charge. --- ### **Significance** - Electric field lines help visualize the electric field. - They act as a "map" that conveys information about the field's **strength** and **direction** at various points. --- ### **Characteristics of Electric Field Lines** 1. **Direction of Field Lines**: - **Radially outward** for a positive charge. - **Radially inward** for a negative charge. ![[Pasted image 20241130091600.png]] 2. **Origination and Termination**: - Field lines originate from a positive charge and terminate on a negative charge. ![[Pasted image 20241130091649.png]] 3. **Indication of Strength**: - The density of field lines indicates the field strength. It increases as we move radially inward and decreases outward. 4. **No Intersecting Lines**: - Field lines never intersect because a single point cannot have two directions of the field. 5. **Interaction with Conductors**: - Field lines cannot pass through a conductor, making the electric field zero inside a conductor. 6. **Length and Tension**: - Field lines tend to contract in length, explaining the attraction between oppositely charged bodies. 7. **Field Line Density**: - The number of field lines passing through a unit area perpendicular to the field is proportional to the magnitude of the electric field at that point. 8. **Tangent to Field Lines**: - The tangent to a field line at any point gives the direction of the electric field at that point. ![[Pasted image 20241130091720.png]] 9. **Resultant Intensity**: - At some points, the resultant intensity is equal to the sum of intensities due to positive and negative charges. The direction aligns with the tangent to the field. 10. **Neutral Points**: - Points where the resultant intensity of the electric field is zero are known as **neutral points**. --- ## **Uniform and Non-Uniform Electric Fields** ### **Uniform Electric Field** A field where the strength remains the same at all points is called a **uniform electric field**. - Example: The field between two infinitely large parallel charged plates. --- ### **Non-Uniform Electric Field** A field where the magnitude and direction of the electric intensity vary at different points is called a **non-uniform electric field**. - Example: The field around a curved sheet of charges. --- ## **Electric Field Between Two Parallel Plates** Consider two infinitely large parallel plates separated by a small distance: - The **upper plate** has a uniform positive charge distribution, and the **lower plate** has a uniform negative charge distribution. - Field lines start from the positive plate and terminate at the negative plate. - At the **ends of the plates**, the field lines bulge out slightly, creating a **fringing field**, indicating the field is non-uniform near the edges. ![[Pasted image 20241130091754.png]] --- ## **Electric Field on the Surface of a Metal Plate** If a charge $+q$ is placed near a metal plate: 1. The positive charge attracts the negative charges (electrons) in the metal plate. 2. These charges move until some reach the surface of the plate closest to $+q$ and come to rest. 3. The electric field lines originating from $+q$ terminate on the negative charges of the metal plate. 4. These lines are always perpendicular to the surface of the metal. --- ## **Summary** ### **Key Points** | **Concept** | **Details** | |----------------------------------|-----------------------------------------------------------------------------| | **Electric Field Lines** | Represent the field's strength and direction. | | **Characteristics** | Radial direction, non-intersecting, proportional to field strength. | | **Uniform Field** | Field strength is constant (e.g., between parallel plates). | | **Non-Uniform Field** | Field strength varies (e.g., around a curved sheet of charge). | | **Field at Metal Plate Surface** | Field lines are perpendicular to the surface due to charge redistribution. | Electric field lines provide an intuitive and visual representation of electric fields, making them essential in understanding field behavior around charges and conductors. --- ## **References**