Current and Potential Difference

Current and Potential Difference

Current

  • Current is the flow of electric charge. It is measured in amperes (A).
  • The flow of current is from positive (+) to negative (-) terminal, opposite to the direction of electron movement.
  • Current is measured using an ammeter. It is always connected in series in a circuit.

Potential Difference

  • Potential difference, also known as voltage, is the work done to move a unit charge from one point to another. It is measured in volts (V).
  • Potential difference is responsible for making current flow in electrical circuits.
  • Potential difference is measured using a voltmeter, which is always connected in parallel in a circuit.

Ohm’s Law

  • Ohm’s law states that the current flowing through a conductor between two points is directly proportional to the potential difference across the two points.
  • It can be mathematically written as I = V/R, where I is current, V is potential difference, and R is resistance.
  • The unit of resistance is ohm (Ω).

Resistors

  • Resistors are used in circuits to limit the flow of current.
  • The resistivity of a material is a measure of how much it resists the flow of current.
  • Factors affecting resistance include: the material, length, cross-sectional area of the conductor, and temperature.

Power and Energy in Circuits

  • Power (P) in a circuit can be calculated using P = IV, where I is the current and V is potential difference. The unit of power is watt (W).
  • The energy (E) transferred in a circuit can be calculated using E = IVt, where I is current, V is potential difference and t is time in seconds. Energy is measured in joules (J).

Series and Parallel Circuits

  • In a series circuit, the same current flows through each component, but the potential differences across them may vary.
  • In a parallel circuit, the potential difference across each component is the same, but the current through them may vary.

Remember these basic principles and laws, as they form the foundation of understanding electricity and magnetism. Good luck with your revision.