Sunday, November 1, 2015

Electricity

  1. An electric iron has a rating of 750 W, 220 v. calculate:
    • Current passing through it; and
    • Its resistance; when in use. 
  2. An electric iron has a rating of 1000 W and 220 V. When in use calculate for it
    • Current passing through it,
    • Its resistance.
  3. An immersion heater has a rating of 2 Kw, 220 V While in use calculate
    • Current passing through it, and
    • Its resistance.
  4. An electric lamp is marked 100 W, 220 V. It is used for 2 hours daily Calculate:   
    • Its resistance while glowing.
    • Energy consumed in KWH per day.
  5. An electric lamp is marked 40 W, 220V. It is used for 4 hours daily. Calculate
    • Its resistance while glowing.
    • Energy consumed in KWH per day.
  6. An electronic lamp is marked 25 W. 220V, It is used for 10 hours daily. Calculate
    • Its resistance while glowing.
    • Energy consumed in KWH per day.
  7. (i) Draw a diagram to show how two resistors R1 and R2 are connected in                 series.    
(ii) In a circuit of two resistors 5 ohm and 10 ohm are connected in series, how does the current passing through the two resistors compare?
  1. A bulb is rated at 5.0 volt, 100 ma. Calculate its 
·         Power and
·         Resistance.
  1. An electric heater is used everyday for 120 minutes. The electricity bill for 30 days is 60 units. Calculate the power of the electric heater.
  2.  Name the unit used in selling electrical energy to consumers. Two lamps , one rates 100 W at 220 V and the other 40 W at 220V are connected in parallel to a 220V main supply line.
  3.  In a household 5 tube lights of 40 W each are used for 5 hours and an electric press of 500 W for 4 hours everyday. Calculate the total electrical energy consumed by the tube lights and press in a month of 0 days.
  4.  A torch bulb is rated 2.5 v and 750 ma. Calculate
·         Its power
·         Its resistance
·         The energy consumed if this bulb is lighted for 4 hours.
  1. Two electric lamps of 100 W and 25 W respectively are connected in parallel to a supply voltage of 200 V. Calculate the total current flowing through the circuit.






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