Electric-Potential

ELECTRIC POTENTIAL

Definition

  • Electric Potential (V): The electric potential is defined as the electric potential energy per unit charge.

    • Formula: V = PE/q

  • Expresses the effect of an electric field from a source based on location.

  • Scalar quantity, and work can be positive or negative.

    • Positive Work: External force does work (charge moves against the electric field).

    • Negative Work: Electric field does work (charge moves with the direction of the electric field).

Electric Field Example

  • Consider a positively charged Van de Graaff generator:

    • Moving a positive test charge towards the sphere requires work against the electric field.

    • The work depends on the amount of charge being moved, as per Coulomb's law.

    • Greater charge means stronger repulsive force, resulting in more work to move the charge the same distance.

Calculation of Electric Potential

  • Formula: V = k * (Q/r)

    • Where:

      • k: Coulomb's constant

      • Q: Magnitude of point charge

      • r: Distance from the charge within the electric field.

ELECTRIC POTENTIAL DIFFERENCE

  • Electric Potential Difference: The difference in electric potential between two locations related to work done moving a charge.

    • Formula: [not explicitly provided in documentation]

  • Units: Measured in Volts (V), where 1 Volt = 1 Joule/Coulomb (J/C).

Charge Movement in Circuits

  • High Potential to Low Potential: Moving a positive test charge from the negative to the positive terminal involves work, increasing potential energy.

  • Moving with the electric field (positive terminal to negative) allows charge to lose potential energy without requiring work.

Electric Potential in Circuits

  • Battery Role:

    • The positive terminal has a voltage rating equal to its electric potential.

    • The battery pumps charge from low to high voltage, establishing potential difference across the circuit.

  • Current flow converts electric potential energy into light and heat, resulting in a voltage drop.

Check Your Understanding

  1. Statements about flashlight electrical circuits:

    • (b) The battery supplies the charge (electrons) that moves through the wires.

    • (e) The battery supplies energy that raises charge from low to high voltage.

  2. Comparing electric potential at points in a circuit based on a diagram (answer varies).

  3. Analogies in circuits:

    • Battery = pump that moves water in a water park analogy.

  4. Battery voltage comparison:

    • Voltage = water pressure in the circuit analogy.

EXAMPLES OF CALCULATIONS

  • Example 1: Calculate electric potential of 25.0 nC at various distances (1.00 m, 2.00 m, infinite).

  • Example 2: Find electric potential at point P affected by two point charges (2.00 µC and 8.00 µC separated by 5.00 mm).

Electric Potential Energy

  • Electric Potential Energy (PEe) is defined as the work needed to bring a charge from infinity to a point in an electric field.

    • Formula: PEe = q * V

  • Calculates the potential energy of a charge at specific locations.

EQUIPOTENTIAL LINES

  • Definition: Lines representing equal electric potential, similar to contour lines on a map.

    • Always perpendicular to electric field lines.

  • Movement: No work done when moving along an equipotential line/surface.

Types of Equipotential Lines

  • Constant Field: In parallel plates like in capacitors, electric field lines are perpendicular, and equipotential lines are parallel.

  • Point Charge: Equipotential lines for a point charge are circular, forming spheres around the charge; voltage scaling shown by spacing of lines.