12. Electricity Science class 10 in English Medium ncert book solutions Chapter Review

Chapter Review:

• A continuous and closed path of an electric current is called an
  electric circuit.
• In an electric circuit the direction of electric current is taken as opposite to the direction of the flow of electrons, which are negative charges.
• The SI unit of electric charge is coulomb (C).
• An electron possesses a negative charge of 1.6 × 10^-19 C.
• The electric current is expressed by a unit called ampere (A).
• The SI unit of electric potential difference is volt (V).
• The potential difference is measured by means of an instrument called the voltmeter. The voltmeter is always connected in parallel across the points between which the potential difference is to be measured.
• Ammeter is an instrument used to measure the electric current in a
  circuit.It is always connected in series in a circuit.
• The electric current flowingthrough a metallic wire is directly proportional to the potential difference V, across its ends provided its temperature remains the same. This is called Ohm’s law..
• A conductor having some appreciable resistance is called a resistor.
• The SI unit of resistivity is Ω m.
• If the electric circuit is purely resistive, that is, a configuration of
  resistors only connected to a battery; the source energy continually gets dissipated entirely in the form of heat. This is known as the heating effect of electric current.
• The unit of power is watt (W). One watt of power is consumed when 1 A of current flows at a potential difference of 1 V.
• The commercial unit of electrical energy is kilowatt hour (kWh).
  1 kW h = 3,600,000 J = 3.6 × 10⁶J.