Because Electric field can be expressed as the gradient of a scalar. Curl of a gradient is always zero by rules of vector calculus.
A vector field is considered conservative when its curl is zero.
When the electric field is zero, it means there is no change in electrical potential across the field. In other words, the equipotential surfaces are parallel, indicating a constant electrical potential. This relationship arises from the fact that the electric field is the negative gradient of the electrical potential.
If the potential is constant through a given region of space, the electric field is zero in that region. This is because the electric field is the negative gradient of the electric potential, so if the potential is not changing, the field becomes zero.
In polar coordinates, the curl of a vector field represents how much the field is rotating around a point. The relationship between the curl and the representation in polar coordinates is that the curl can be calculated using the polar coordinate system to determine the rotational behavior of the vector field.
Zero, because the electric field inside a charged hollow sphere is zero. This is due to the Gauss's law and symmetry of the charged hollow sphere, which results in no net electric field inside the sphere.