Introduction
When a semi-infinite insulating rod has linear charge density lambda, it creates an electric field perpendicular to it. In this guide, we will explain in detail how to calculate the electric field at point P.

Calculating Electric Field at Point P
To calculate the electric field at point P, we need to use Coulomb's law. Coulomb's law states that the electric force between two charges is proportional to the product of the charges and inversely proportional to the square of the distance between them.

Calculating Electric Field Due to an Infinitely Long Rod
To calculate the electric field due to an infinitely long rod, we use Gauss's law. Gauss's law states that the electric flux through any closed surface is equal to the charge enclosed by the surface divided by the permittivity of free space.

Calculating Electric Field Due to a Semi-Infinite Rod
To calculate the electric field due to a semi-infinite rod, we need to use a combination of Coulomb's law and Gauss's law. We can break the semi-infinite rod into two parts - an infinitely long part and a finite part.

Conclusion
In conclusion, the electric field at point P due to a semi-infinite insulating rod with linear charge density lambda can be calculated using a combination of Coulomb's law and Gauss's law. By breaking the semi-infinite rod into two parts and using the appropriate equations, we can calculate the electric field at point P with accuracy.