Electricity

• The SI unit of current is ampere (A).
• A current is the flow of charge through an object.
• Electric current is the amount of charge flowing through a particular area in a unit time.
• Voltmeter

  • An instrument used to measure voltage or potential difference between two points in an electric circuit.
  • It is always connected in parallel.
• Ammeter

  • An instrument for measuring electric current in amperes.
  • It is always connected in series.
• Ohm's law states that the potential difference across ends of a given resistor is directly proportional to the current flowing through it, provided its temperature remains the same.

  $V=$$IR$
• One ampere is constituted by the flow of one coulomb of charge per second.

  $1A=$$1C/1s$
• Resistance is a measure of the opposition to current flow in an electrical circuit.

  It's SI unit is ohm (Ω).

  $1ohm=$$1volt/1 ampere$
• Resistance of a conductor depends on:

  1. It's length
  2. the nature of it's material
  3. it's area of cross-section
• Heating Effect of Electric Current:

  When an electric current passes through a conductor (like a high resistance wire)the conductor becomes hot after sometime and produces heat.
• The electrical energy dissipated in a resistor is given by

  $W=$$V*$$I*$$t$
• The unit of power is watt (W).

  One watt of power is consumed when 1A of current flows at a potential difference of 1V.
• SI unit of power is watt (w).