Can electric potential be negative and equipotential lines always cross in 90 degrees the electric field lines?
Yes, electric potential can be negative. Electric potential is a scalar quantity that represents the amount of potential energy per unit charge at a given point in an electric field. It is measured in volts (V). The electric potential is negative at a point if the force on a positive charge at that point would be directed towards a point of lower potential.
Equipotential lines are imaginary lines drawn in an electric field such that at every point on a given line, the electric potential is the same. Equipotential lines do not always cross electric field lines at 90 degrees. The angle between an equipotential line and an electric field line is equal to the angle between the gradient of the potential and the electric field. The gradient of the potential is a vector that points in the direction of the greatest increase in potential. The electric field is a vector that points in the direction of the force on a positive charge. The angle between the gradient of the potential and the electric field can be any angle, including 0 degrees, 90 degrees, or 180 degrees.
Equipotential lines are imaginary lines drawn in an electric field such that at every point on a given line, the electric potential is the same. Equipotential lines do not always cross electric field lines at 90 degrees. The angle between Electric field and an equipotential surface is always 900. This is because, when the potential becomes constant, the negative potential gradient also becomes zero, hence necessitating the need for Electric field to be always normal with surface. If all points along an equipotential line are at the same potential, then no charge would move along them. The electric field line shows the direction of the electrostatic force on a charge. Since there's no component of force along an equipotential line, field lines must intersect them at right angles. An equipotential surface is a three-dimensional version of equipotential lines. Equipotential lines are always perpendicular to electric field lines. The process by which a conductor can be fixed at zero volts by connecting it to the earth with a good conductor is grounding. Now θ = 90o means that the angle between electric lines of forces or electric field and the equipotential surface is 900. The angle of the intersection between each flow line and the equipotential line must be 90° which means they should be orthogonal to each other. Two flow lines or two equipotential lines can never cross each other. An equal quantity of seepage occurs in each flow channel.